| Age | Commit message (Collapse) | Author |
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syzbot wrote:
> ========================================================
> WARNING: possible irq lock inversion dependency detected
> 5.6.0-syzkaller #0 Not tainted
> --------------------------------------------------------
> swapper/1/0 just changed the state of lock:
> ffffffff898090d8 (tasklist_lock){.+.?}-{2:2}, at: send_sigurg+0x9f/0x320 fs/fcntl.c:840
> but this lock took another, SOFTIRQ-unsafe lock in the past:
> (&pid->wait_pidfd){+.+.}-{2:2}
>
>
> and interrupts could create inverse lock ordering between them.
>
>
> other info that might help us debug this:
> Possible interrupt unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> lock(&pid->wait_pidfd);
> local_irq_disable();
> lock(tasklist_lock);
> lock(&pid->wait_pidfd);
> <Interrupt>
> lock(tasklist_lock);
>
> *** DEADLOCK ***
>
> 4 locks held by swapper/1/0:
The problem is that because wait_pidfd.lock is taken under the tasklist
lock. It must always be taken with irqs disabled as tasklist_lock can be
taken from interrupt context and if wait_pidfd.lock was already taken this
would create a lock order inversion.
Oleg suggested just disabling irqs where I have added extra calls to
wait_pidfd.lock. That should be safe and I think the code will eventually
do that. It was rightly pointed out by Christian that sharing the
wait_pidfd.lock was a premature optimization.
It is also true that my pre-merge window testing was insufficient. So
remove the premature optimization and give struct pid a dedicated lock of
it's own for struct pid things. I have verified that lockdep sees all 3
paths where we take the new pid->lock and lockdep does not complain.
It is my current day dream that one day pid->lock can be used to guard the
task lists as well and then the tasklist_lock won't need to be held to
deliver signals. That will require taking pid->lock with irqs disabled.
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/lkml/00000000000011d66805a25cd73f@google.com/
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Reported-by: syzbot+343f75cdeea091340956@syzkaller.appspotmail.com
Reported-by: syzbot+832aabf700bc3ec920b9@syzkaller.appspotmail.com
Reported-by: syzbot+f675f964019f884dbd0f@syzkaller.appspotmail.com
Reported-by: syzbot+a9fb1457d720a55d6dc5@syzkaller.appspotmail.com
Fixes: 7bc3e6e55acf ("proc: Use a list of inodes to flush from proc")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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Replace the 32bit exec_id with a 64bit exec_id to make it impossible
to wrap the exec_id counter. With care an attacker can cause exec_id
wrap and send arbitrary signals to a newly exec'd parent. This
bypasses the signal sending checks if the parent changes their
credentials during exec.
The severity of this problem can been seen that in my limited testing
of a 32bit exec_id it can take as little as 19s to exec 65536 times.
Which means that it can take as little as 14 days to wrap a 32bit
exec_id. Adam Zabrocki has succeeded wrapping the self_exe_id in 7
days. Even my slower timing is in the uptime of a typical server.
Which means self_exec_id is simply a speed bump today, and if exec
gets noticably faster self_exec_id won't even be a speed bump.
Extending self_exec_id to 64bits introduces a problem on 32bit
architectures where reading self_exec_id is no longer atomic and can
take two read instructions. Which means that is is possible to hit
a window where the read value of exec_id does not match the written
value. So with very lucky timing after this change this still
remains expoiltable.
I have updated the update of exec_id on exec to use WRITE_ONCE
and the read of exec_id in do_notify_parent to use READ_ONCE
to make it clear that there is no locking between these two
locations.
Link: https://lore.kernel.org/kernel-hardening/20200324215049.GA3710@pi3.com.pl
Fixes: 2.3.23pre2
Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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This is an infrastructure change that makes way for fixing this issue.
Each patch was already posted previously so this is just a cleanup of
the original mailing list thread(s) which got out of control by now.
Everything started here:
https://lore.kernel.org/lkml/AM6PR03MB5170B06F3A2B75EFB98D071AE4E60@AM6PR03MB5170.eurprd03.prod.outlook.com/
I added reviewed-by tags from the mailing list threads, except when
withdrawn.
It took a lot longer than expected to collect everything from the
mailinglist threads, since several commit messages have been infected
with typos, and they got fixed without a new patch version.
- Correct the point of no return.
- Add two new mutexes to replace cred_guard_mutex.
- Fix each use of cred_guard_mutex.
- Update documentation.
- Add a test case.
-- EWB Removed the last 2 patches they need more work
Bernd Edlinger (9):
exec: Fix a deadlock in strace
selftests/ptrace: add test cases for dead-locks
mm: docs: Fix a comment in process_vm_rw_core
kernel: doc: remove outdated comment cred.c
kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve
proc: Use new infrastructure to fix deadlocks in execve
proc: io_accounting: Use new infrastructure to fix deadlocks in execve
perf: Use new infrastructure to fix deadlocks in execve
pidfd: Use new infrastructure to fix deadlocks in execve
Eric W. Biederman (5):
exec: Only compute current once in flush_old_exec
exec: Factor unshare_sighand out of de_thread and call it separately
exec: Move cleanup of posix timers on exec out of de_thread
exec: Move exec_mmap right after de_thread in flush_old_exec
exec: Add exec_update_mutex to replace cred_guard_mutex
fs/exec.c | 78 +++++++++++++++++++---------
fs/proc/base.c | 10 ++--
include/linux/binfmts.h | 8 ++-
include/linux/sched/signal.h | 9 +++-
init/init_task.c | 1 +
kernel/cred.c | 2 -
kernel/events/core.c | 12 ++---
kernel/fork.c | 5 +-
kernel/kcmp.c | 8 +--
kernel/pid.c | 4 +-
mm/process_vm_access.c | 2 +-
tools/testing/selftests/ptrace/Makefile | 4 +-
tools/testing/selftests/ptrace/vmaccess.c | 86 +++++++++++++++++++++++++++++++
13 files changed, 179 insertions(+), 50 deletions(-)
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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This changes __pidfd_fget to use the new exec_update_mutex
instead of cred_guard_mutex.
This should be safe, as the credentials do not change
before exec_update_mutex is locked. Therefore whatever
file access is possible with holding the cred_guard_mutex
here is also possbile with the exec_update_mutex.
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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This changes perf_event_set_clock to use the new exec_update_mutex
instead of cred_guard_mutex.
This should be safe, as the credentials are only used for reading.
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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This changes do_io_accounting to use the new exec_update_mutex
instead of cred_guard_mutex.
This fixes possible deadlocks when the trace is accessing
/proc/$pid/io for instance.
This should be safe, as the credentials are only used for reading.
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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This changes lock_trace to use the new exec_update_mutex
instead of cred_guard_mutex.
This fixes possible deadlocks when the trace is accessing
/proc/$pid/stack for instance.
This should be safe, as the credentials are only used for reading,
and task->mm is updated on execve under the new exec_update_mutex.
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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This changes kcmp_epoll_target to use the new exec_update_mutex
instead of cred_guard_mutex.
This should be safe, as the credentials are only used for reading,
and furthermore ->mm and ->sighand are updated on execve,
but only under the new exec_update_mutex.
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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This removes an outdated comment in prepare_kernel_cred.
There is no "cred_replace_mutex" any more, so the comment must
go away.
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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This removes a duplicate "a" in the comment in process_vm_rw_core.
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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This adds test cases for ptrace deadlocks.
Additionally fixes a compile problem in get_syscall_info.c,
observed with gcc-4.8.4:
get_syscall_info.c: In function 'get_syscall_info':
get_syscall_info.c:93:3: error: 'for' loop initial declarations are only
allowed in C99 mode
for (unsigned int i = 0; i < ARRAY_SIZE(args); ++i) {
^
get_syscall_info.c:93:3: note: use option -std=c99 or -std=gnu99 to compile
your code
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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This fixes a deadlock in the tracer when tracing a multi-threaded
application that calls execve while more than one thread are running.
I observed that when running strace on the gcc test suite, it always
blocks after a while, when expect calls execve, because other threads
have to be terminated. They send ptrace events, but the strace is no
longer able to respond, since it is blocked in vm_access.
The deadlock is always happening when strace needs to access the
tracees process mmap, while another thread in the tracee starts to
execve a child process, but that cannot continue until the
PTRACE_EVENT_EXIT is handled and the WIFEXITED event is received:
strace D 0 30614 30584 0x00000000
Call Trace:
__schedule+0x3ce/0x6e0
schedule+0x5c/0xd0
schedule_preempt_disabled+0x15/0x20
__mutex_lock.isra.13+0x1ec/0x520
__mutex_lock_killable_slowpath+0x13/0x20
mutex_lock_killable+0x28/0x30
mm_access+0x27/0xa0
process_vm_rw_core.isra.3+0xff/0x550
process_vm_rw+0xdd/0xf0
__x64_sys_process_vm_readv+0x31/0x40
do_syscall_64+0x64/0x220
entry_SYSCALL_64_after_hwframe+0x44/0xa9
expect D 0 31933 30876 0x80004003
Call Trace:
__schedule+0x3ce/0x6e0
schedule+0x5c/0xd0
flush_old_exec+0xc4/0x770
load_elf_binary+0x35a/0x16c0
search_binary_handler+0x97/0x1d0
__do_execve_file.isra.40+0x5d4/0x8a0
__x64_sys_execve+0x49/0x60
do_syscall_64+0x64/0x220
entry_SYSCALL_64_after_hwframe+0x44/0xa9
This changes mm_access to use the new exec_update_mutex
instead of cred_guard_mutex.
This patch is based on the following patch by Eric W. Biederman:
"[PATCH 0/5] Infrastructure to allow fixing exec deadlocks"
Link: https://lore.kernel.org/lkml/87v9ne5y4y.fsf_-_@x220.int.ebiederm.org/
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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The cred_guard_mutex is problematic as it is held over possibly
indefinite waits for userspace. The possible indefinite waits for
userspace that I have identified are: The cred_guard_mutex is held in
PTRACE_EVENT_EXIT waiting for the tracer. The cred_guard_mutex is
held over "put_user(0, tsk->clear_child_tid)" in exit_mm(). The
cred_guard_mutex is held over "get_user(futex_offset, ...") in
exit_robust_list. The cred_guard_mutex held over copy_strings.
The functions get_user and put_user can trigger a page fault which can
potentially wait indefinitely in the case of userfaultfd or if
userspace implements part of the page fault path.
In any of those cases the userspace process that the kernel is waiting
for might make a different system call that winds up taking the
cred_guard_mutex and result in deadlock.
Holding a mutex over any of those possibly indefinite waits for
userspace does not appear necessary. Add exec_update_mutex that will
just cover updating the process during exec where the permissions and
the objects pointed to by the task struct may be out of sync.
The plan is to switch the users of cred_guard_mutex to
exec_update_mutex one by one. This lets us move forward while still
being careful and not introducing any regressions.
Link: https://lore.kernel.org/lkml/20160921152946.GA24210@dhcp22.suse.cz/
Link: https://lore.kernel.org/lkml/AM6PR03MB5170B06F3A2B75EFB98D071AE4E60@AM6PR03MB5170.eurprd03.prod.outlook.com/
Link: https://lore.kernel.org/linux-fsdevel/20161102181806.GB1112@redhat.com/
Link: https://lore.kernel.org/lkml/20160923095031.GA14923@redhat.com/
Link: https://lore.kernel.org/lkml/20170213141452.GA30203@redhat.com/
Ref: 45c1a159b85b ("Add PTRACE_O_TRACEVFORKDONE and PTRACE_O_TRACEEXIT facilities.")
Ref: 456f17cd1a28 ("[PATCH] user-vm-unlock-2.5.31-A2")
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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I have read through the code in exec_mmap and I do not see anything
that depends on sighand or the sighand lock, or on signals in anyway
so this should be safe.
This rearrangement of code has two significant benefits. It makes
the determination of passing the point of no return by testing bprm->mm
accurate. All failures prior to that point in flush_old_exec are
either truly recoverable or they are fatal.
Further this consolidates all of the possible indefinite waits for
userspace together at the top of flush_old_exec. The possible wait
for a ptracer on PTRACE_EVENT_EXIT, the possible wait for a page fault
to be resolved in clear_child_tid, and the possible wait for a page
fault in exit_robust_list.
This consolidation allows the creation of a mutex to replace
cred_guard_mutex that is not held over possible indefinite userspace
waits. Which will allow removing deadlock scenarios from the kernel.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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These functions have very little to do with de_thread move them out
of de_thread an into flush_old_exec proper so it can be more clearly
seen what flush_old_exec is doing.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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This makes the code clearer and makes it easier to implement a mutex
that is not taken over any locations that may block indefinitely waiting
for userspace.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Make it clear that current only needs to be computed once in
flush_old_exec. This may have some efficiency improvements and it
makes the code easier to change.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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accidentally broke it in the middle 2016.
The problem is that because we perform an internal mount of proc
before user space mounts proc all of the mount options that user
specifies when mounting proc are ignored.
You can set those mount options with a remount but that is rather
surprising.
This most directly affects android which is using hidpid=2 by default.
Now that the sysctl system call support has been removed, and we have
settled on way of flushing proc dentries when a process exits without
using proc_mnt, there is an simple and easy fix.
a) Give UML mconsole it's own private mount of proc to use.
b) Stop creating the internal mount of proc
We still need Alexey Gladkov's full patch to get proc mount options to
work inside of UML, and to be generally useful. This set of changes
is just enough to get them working as well as they have in the past.
If anyone sees any problem with this code please let me know.
Otherwise I plan to merge these set of fixes through my tree.
Link: https://lore.kernel.org/lkml/87r21tuulj.fsf@x220.int.ebiederm.org/
Link: https://lore.kernel.org/lkml/871rqk2brn.fsf_-_@x220.int.ebiederm.org/
Link: https://lore.kernel.org/lkml/20200210150519.538333-1-gladkov.alexey@gmail.com/
Link: https://lore.kernel.org/lkml/20180611195744.154962-1-astrachan@google.com/
Fixes: e94591d0d90c ("proc: Convert proc_mount to use mount_ns.")
Eric W. Biederman (4):
uml: Don't consult current to find the proc_mnt in mconsole_proc
uml: Create a private mount of proc for mconsole
proc: Remove the now unnecessary internal mount of proc
pid: Improve the comment about waiting in zap_pid_ns_processes
arch/um/drivers/mconsole_kern.c | 28 +++++++++++++++++++++++++++-
fs/proc/root.c | 36 ------------------------------------
include/linux/pid_namespace.h | 2 --
include/linux/proc_ns.h | 5 -----
kernel/pid.c | 8 --------
kernel/pid_namespace.c | 38 +++++++++++++++++++-------------------
6 files changed, 46 insertions(+), 71 deletions(-)
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Oleg wrote a very informative comment, but with the removal of
proc_cleanup_work it is no longer accurate.
Rewrite the comment so that it only talks about the details
that are still relevant, and hopefully is a little clearer.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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There remains no more code in the kernel using pids_ns->proc_mnt,
therefore remove it from the kernel.
The big benefit of this change is that one of the most error prone and
tricky parts of the pid namespace implementation, maintaining kernel
mounts of proc is removed.
In addition removing the unnecessary complexity of the kernel mount
fixes a regression that caused the proc mount options to be ignored.
Now that the initial mount of proc comes from userspace, those mount
options are again honored. This fixes Android's usage of the proc
hidepid option.
Reported-by: Alistair Strachan <astrachan@google.com>
Fixes: e94591d0d90c ("proc: Convert proc_mount to use mount_ns.")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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The mconsole code only ever accesses proc for the initial pid
namespace. Instead of depending upon the proc_mnt which is
for proc_flush_task have uml create it's own mount of proc
instead.
This allows proc_flush_task to evolve and remove the
need for having a proc_mnt to do it's job.
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Inspection of the control flow reveals that mconsole_proc is either
called from mconsole_stop called from mc_work_proc or from
mc_work_proc directly. The function mc_work_proc is dispatched to a
kernel thread with schedule_work.
All of the threads that run dispatched by schedule_work are in the
init pid namespace.
So make the code clearer and by using init_pid_ns instead of
task_active_pid_ns(current).
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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Cleanly handling proc mount options require the internal mount of
proc to be removed (so mount options are not ignored), and quite
possibly multiple proc superblocks per pid namespace (so a
second mount of proc does not silently get the mount options of the
first mount of proc. In either case being able to flush proc
dentries on process exit needs to be made to work without going
through proc_mnt. After serveral discussions this is the set
of changes that work and no one objects to.
---
I have addressed all of the review comments as I understand them,
and fixed the small oversight the kernel test robot was able to
find. (I had failed to initialize the new field pid->inodes).
I did not hear any concerns from the 10,000 foot level last time
so I am assuming this set of changes (baring bugs) is good to go.
Unless some new issues appear my plan is to put this in my tree
and get this into linux-next. Which will give Alexey something
to build his changes on.
I tested this set of changes by running:
(while ls -1 -f /proc > /dev/null ; do :; done ) &
And monitoring the amount of free memory.
With the flushing disabled I saw the used memory in the system grow by
20M before the shrinker would bring it back down to where it started.
With the patch applied I saw the memory usage stay essentially fixed.
So flushing definitely keeps things working better.
Eric W. Biederman (6):
proc: Rename in proc_inode rename sysctl_inodes sibling_inodes
proc: Generalize proc_sys_prune_dcache into proc_prune_siblings_dcache
proc: In proc_prune_siblings_dcache cache an aquired super block
proc: Use d_invalidate in proc_prune_siblings_dcache
proc: Clear the pieces of proc_inode that proc_evict_inode cares about
proc: Use a list of inodes to flush from proc
fs/proc/base.c | 111 ++++++++++++++++--------------------------------
fs/proc/inode.c | 73 ++++++++++++++++++++++++++++---
fs/proc/internal.h | 4 +-
fs/proc/proc_sysctl.c | 45 +++-----------------
include/linux/pid.h | 1 +
include/linux/proc_fs.h | 4 +-
kernel/exit.c | 4 +-
kernel/pid.c | 1 +
8 files changed, 120 insertions(+), 123 deletions(-)
Link: https://lore.kernel.org/lkml/871rqk2brn.fsf_-_@x220.int.ebiederm.org/
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Merge branch 'proc-dentry-flushing-without-proc-mnt-v2' into HEAD
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Rework the flushing of proc to use a list of directory inodes that
need to be flushed.
The list is kept on struct pid not on struct task_struct, as there is
a fixed connection between proc inodes and pids but at least for the
case of de_thread the pid of a task_struct changes.
This removes the dependency on proc_mnt which allows for different
mounts of proc having different mount options even in the same pid
namespace and this allows for the removal of proc_mnt which will
trivially the first mount of proc to honor it's mount options.
This flushing remains an optimization. The functions
pid_delete_dentry and pid_revalidate ensure that ordinary dcache
management will not attempt to use dentries past the point their
respective task has died. When unused the shrinker will
eventually be able to remove these dentries.
There is a case in de_thread where proc_flush_pid can be
called early for a given pid. Which winds up being
safe (if suboptimal) as this is just an optiimization.
Only pid directories are put on the list as the other
per pid files are children of those directories and
d_invalidate on the directory will get them as well.
So that the pid can be used during flushing it's reference count is
taken in release_task and dropped in proc_flush_pid. Further the call
of proc_flush_pid is moved after the tasklist_lock is released in
release_task so that it is certain that the pid has already been
unhashed when flushing it taking place. This removes a small race
where a dentry could recreated.
As struct pid is supposed to be small and I need a per pid lock
I reuse the only lock that currently exists in struct pid the
the wait_pidfd.lock.
The net result is that this adds all of this functionality
with just a little extra list management overhead and
a single extra pointer in struct pid.
v2: Initialize pid->inodes. I somehow failed to get that
initialization into the initial version of the patch. A boot
failure was reported by "kernel test robot <lkp@intel.com>", and
failure to initialize that pid->inodes matches all of the reported
symptoms.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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This just keeps everything tidier, and allows for using flags like
SLAB_TYPESAFE_BY_RCU where slabs are not always cleared before reuse.
I don't see reuse without reinitializing happening with the proc_inode
but I had a false alarm while reworking flushing of proc dentries and
indoes when a process dies that caused me to tidy this up.
The code is a little easier to follow and reason about this
way so I figured the changes might as well be kept.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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The function d_prune_aliases has the problem that it will only prune
aliases thare are completely unused. It will not remove aliases for
the dcache or even think of removing mounts from the dcache. For that
behavior d_invalidate is needed.
To use d_invalidate replace d_prune_aliases with d_find_alias followed
by d_invalidate and dput.
For completeness the directory and the non-directory cases are
separated because in theory (although not in currently in practice for
proc) directories can only ever have a single dentry while
non-directories can have hardlinks and thus multiple dentries.
As part of this separation use d_find_any_alias for directories
to spare d_find_alias the extra work of doing that.
Plus the differences between d_find_any_alias and d_find_alias makes
it clear why the directory and non-directory code and not share code.
To make it clear these routines now invalidate dentries rename
proc_prune_siblings_dache to proc_invalidate_siblings_dcache, and rename
proc_sys_prune_dcache proc_sys_invalidate_dcache.
V2: Split the directory and non-directory cases. To make this
code robust to future changes in proc.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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Because there are likely to be several sysctls in a row on the
same superblock cache the super_block after the count has
been raised and don't deactivate it until we are processing
another super_block.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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This prepares the way for allowing the pid part of proc to use this
dcache pruning code as well.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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I about to need and use the same functionality for pid based
inodes and there is no point in adding a second field when
this field is already here and serving the same purporse.
Just give the field a generic name so it is clear that
it is no longer sysctl specific.
Also for good measure initialize sibling_inodes when
proc_inode is initialized.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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Pull IPMI update from Corey Minyard:
"Minor bug fixes for IPMI
I know this is late; I've been travelling and, well, I've been
distracted.
This is just a few bug fixes and adding i2c support to the IPMB
driver, which is something I wanted from the beginning for it"
* tag 'for-linus-5.6-1' of https://github.com/cminyard/linux-ipmi:
drivers: ipmi: fix off-by-one bounds check that leads to a out-of-bounds write
ipmi:ssif: Handle a possible NULL pointer reference
drivers: ipmi: Modify max length of IPMB packet
drivers: ipmi: Support raw i2c packet in IPMB
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Pull KVM fixes from Paolo Bonzini:
"Bugfixes and improvements to selftests.
On top of this, Mauro converted the KVM documentation to rst format,
which was very welcome"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (44 commits)
docs: virt: guest-halt-polling.txt convert to ReST
docs: kvm: review-checklist.txt: rename to ReST
docs: kvm: Convert timekeeping.txt to ReST format
docs: kvm: Convert s390-diag.txt to ReST format
docs: kvm: Convert ppc-pv.txt to ReST format
docs: kvm: Convert nested-vmx.txt to ReST format
docs: kvm: Convert mmu.txt to ReST format
docs: kvm: Convert locking.txt to ReST format
docs: kvm: Convert hypercalls.txt to ReST format
docs: kvm: arm/psci.txt: convert to ReST
docs: kvm: convert arm/hyp-abi.txt to ReST
docs: kvm: Convert api.txt to ReST format
docs: kvm: convert devices/xive.txt to ReST
docs: kvm: convert devices/xics.txt to ReST
docs: kvm: convert devices/vm.txt to ReST
docs: kvm: convert devices/vfio.txt to ReST
docs: kvm: convert devices/vcpu.txt to ReST
docs: kvm: convert devices/s390_flic.txt to ReST
docs: kvm: convert devices/mpic.txt to ReST
docs: kvm: convert devices/arm-vgit.txt to ReST
...
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git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras
Pull EDAC fixes from Borislav Petkov:
"Two fixes for use-after-free and memory leaking in the EDAC core, by
Robert Richter.
Debug options like DEBUG_TEST_DRIVER_REMOVE, KASAN and DEBUG_KMEMLEAK
unearthed issues with the lifespan of memory allocated by the EDAC
memory controller descriptor due to misdesigned memory freeing, done
partially by the EDAC core *and* the driver core, which is problematic
to say the least.
These two are minimal fixes to take care of stable - a proper rework
is following which cleans up that mess properly"
* tag 'edac_urgent_for_5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras:
EDAC/sysfs: Remove csrow objects on errors
EDAC/mc: Fix use-after-free and memleaks during device removal
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Pull block fixes from Jens Axboe:
"Not a lot here, which is great, basically just three small bcache
fixes from Coly, and four NVMe fixes via Keith"
* tag 'block-5.6-2020-02-16' of git://git.kernel.dk/linux-block:
nvme: fix the parameter order for nvme_get_log in nvme_get_fw_slot_info
nvme/pci: move cqe check after device shutdown
nvme: prevent warning triggered by nvme_stop_keep_alive
nvme/tcp: fix bug on double requeue when send fails
bcache: remove macro nr_to_fifo_front()
bcache: Revert "bcache: shrink btree node cache after bch_btree_check()"
bcache: ignore pending signals when creating gc and allocator thread
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git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"Two races fixed, memory leak fix, sysfs directory fixup and two new
log messages:
- two fixed race conditions: extent map merging and truncate vs
fiemap
- create the right sysfs directory with device information and move
the individual device dirs under it
- print messages when the tree-log is replayed at mount time or
cannot be replayed on remount"
* tag 'for-5.6-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: sysfs, move device id directories to UUID/devinfo
btrfs: sysfs, add UUID/devinfo kobject
Btrfs: fix race between shrinking truncate and fiemap
btrfs: log message when rw remount is attempted with unclean tree-log
btrfs: print message when tree-log replay starts
Btrfs: fix race between using extent maps and merging them
btrfs: ref-verify: fix memory leaks
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Pull cifs fixes from Steve French:
"Four small CIFS/SMB3 fixes. One (the EA overflow fix) for stable"
* tag '5.6-rc1-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
cifs: make sure we do not overflow the max EA buffer size
cifs: enable change notification for SMB2.1 dialect
cifs: Fix mode output in debugging statements
cifs: fix mount option display for sec=krb5i
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git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 fixes from Ted Ts'o:
"Miscellaneous ext4 bug fixes (all stable fodder)"
* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: improve explanation of a mount failure caused by a misconfigured kernel
jbd2: do not clear the BH_Mapped flag when forgetting a metadata buffer
jbd2: move the clearing of b_modified flag to the journal_unmap_buffer()
ext4: add cond_resched() to ext4_protect_reserved_inode
ext4: fix checksum errors with indexed dirs
ext4: fix support for inode sizes > 1024 bytes
ext4: simplify checking quota limits in ext4_statfs()
ext4: don't assume that mmp_nodename/bdevname have NUL
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git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
Pull input updates from Dmitry Torokhov:
- a few drivers have been updated to use flexible-array syntax instead
of GCC extension
- ili210x touchscreen driver now supports the 2120 protocol flavor
- a couple more of Synaptics devices have been switched over to RMI4
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
Input: cyapa - replace zero-length array with flexible-array member
Input: tca6416-keypad - replace zero-length array with flexible-array member
Input: gpio_keys_polled - replace zero-length array with flexible-array member
Input: synaptics - remove the LEN0049 dmi id from topbuttonpad list
Input: synaptics - enable SMBus on ThinkPad L470
Input: synaptics - switch T470s to RMI4 by default
Input: gpio_keys - replace zero-length array with flexible-array member
Input: goldfish_events - replace zero-length array with flexible-array member
Input: psmouse - switch to using i2c_new_scanned_device()
Input: ili210x - add ili2120 support
Input: ili210x - fix return value of is_visible function
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Pull rdma fixes from Jason Gunthorpe:
"Not too much going on here, though there are about four fixes related
to stuff merged during the last merge window.
We also see the return of a syzkaller instance with access to RDMA
devices, and a few bugs detected by that squished.
- Fix three crashers and a memory memory leak for HFI1
- Several bugs found by syzkaller
- A bug fix for the recent QP counters feature on older mlx5 HW
- Locking inversion in cxgb4
- Unnecessary WARN_ON in siw
- A umad crasher regression during unload, from a bug fix for
something else
- Bugs introduced in the merge window:
- Missed list_del in uverbs file rework, core and mlx5 devx
- Unexpected integer math truncation in the mlx5 VAR patches
- Compilation bug fix for the VAR patches on 32 bit"
* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma:
IB/mlx5: Use div64_u64 for num_var_hw_entries calculation
RDMA/core: Fix protection fault in get_pkey_idx_qp_list
RDMA/rxe: Fix soft lockup problem due to using tasklets in softirq
RDMA/mlx5: Prevent overflow in mmap offset calculations
IB/umad: Fix kernel crash while unloading ib_umad
RDMA/mlx5: Fix async events cleanup flows
RDMA/core: Add missing list deletion on freeing event queue
RDMA/siw: Remove unwanted WARN_ON in siw_cm_llp_data_ready()
RDMA/iw_cxgb4: initiate CLOSE when entering TERM
IB/mlx5: Return failure when rts2rts_qp_counters_set_id is not supported
RDMA/core: Fix invalid memory access in spec_filter_size
IB/rdmavt: Reset all QPs when the device is shut down
IB/hfi1: Close window for pq and request coliding
IB/hfi1: Acquire lock to release TID entries when user file is closed
RDMA/hfi1: Fix memory leak in _dev_comp_vect_mappings_create
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git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc
Pull ARM SoC fixes from Olof Johansson:
"A handful of fixes that have come in since the merge window:
- Fix of PCI interrupt map on arm64 fast model (SW emulator)
- Fixlet for sound on ST platforms and a small cleanup of deprecated
DT properties
- A stack buffer overflow fix for moxtet
- Fuse driver build fix for Tegra194
- A few config updates to turn on new drivers merged this cycle"
* tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc:
bus: moxtet: fix potential stack buffer overflow
soc/tegra: fuse: Fix build with Tegra194 configuration
ARM: dts: sti: fixup sound frame-inversion for stihxxx-b2120.dtsi
ARM: dts: sti: Remove deprecated snps PHY properties for stih410-b2260
arm64: defconfig: Enable DRM_SUN6I_DSI
arm64: defconfig: Enable CONFIG_SUN8I_THERMAL
ARM: sunxi: Enable CONFIG_SUN8I_THERMAL
arm64: defconfig: Set bcm2835-dma as built-in
ARM: configs: Cleanup old Kconfig options
ARM: npcm: Bring back GPIOLIB support
arm64: dts: fast models: Fix FVP PCI interrupt-map property
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git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Vasily Gorbik:
- Enable paes-s390 cipher selftests in testmgr (acked-by Herbert Xu).
- Fix protected key length update in PKEY_SEC2PROTK ioctl and increase
card/queue requests counter to 64-bit in crypto code.
- Fix clang warning in get_tod_clock.
- Fix ultravisor info length extensions handling.
- Fix style of SPDX License Identifier in vfio-ccw.
- Avoid unnecessary GFP_ATOMIC and simplify ACK tracking in qdio.
* tag 's390-5.6-3' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
crypto/testmgr: enable selftests for paes-s390 ciphers
s390/time: Fix clk type in get_tod_clock
s390/uv: Fix handling of length extensions
s390/qdio: don't allocate *aob array with GFP_ATOMIC
s390/qdio: simplify ACK tracking
s390/zcrypt: fix card and queue total counter wrap
s390/pkey: fix missing length of protected key on return
vfio-ccw: Use the correct style for SPDX License Identifier
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git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging
Pull hwmon fixes from Guenter Roeck:
"Fix compatible string typos in the xdpe12284 driver, and a wrong bit
value in the ltc2978 driver"
* tag 'hwmon-for-v5.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
hwmon: (pmbus/xdpe12284) fix typo in compatible strings
hwmon: (pmbus/ltc2978) Fix PMBus polling of MFR_COMMON definitions.
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
"Misc fixes all over the place:
- Fix NUMA over-balancing between lightly loaded nodes. This is
fallout of the big load-balancer rewrite.
- Fix the NOHZ remote loadavg update logic, which fixes anomalies
like reported 150 loadavg on mostly idle CPUs.
- Fix XFS performance/scalability
- Fix throttled groups unbound task-execution bug
- Fix PSI procfs boundary condition
- Fix the cpu.uclamp.{min,max} cgroup configuration write checks
- Fix DocBook annotations
- Fix RCU annotations
- Fix overly CPU-intensive housekeeper CPU logic loop on large CPU
counts"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Fix kernel-doc warning in attach_entity_load_avg()
sched/core: Annotate curr pointer in rq with __rcu
sched/psi: Fix OOB write when writing 0 bytes to PSI files
sched/fair: Allow a per-CPU kthread waking a task to stack on the same CPU, to fix XFS performance regression
sched/fair: Prevent unlimited runtime on throttled group
sched/nohz: Optimize get_nohz_timer_target()
sched/uclamp: Reject negative values in cpu_uclamp_write()
sched/fair: Allow a small load imbalance between low utilisation SD_NUMA domains
timers/nohz: Update NOHZ load in remote tick
sched/core: Don't skip remote tick for idle CPUs
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Ingo Molnar:
"Fixes and HW enablement patches:
- Tooling fixes, most of which are tooling header synchronization
with v5.6 changes
- Fix kprobes fallout on ARM
- Add Intel Elkhart Lake support and extend Tremont support, these
are relatively simple and should only affect those models
- Fix the AMD family 17h generic event table"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (30 commits)
perf llvm: Fix script used to obtain kernel make directives to work with new kbuild
tools headers kvm: Sync linux/kvm.h with the kernel sources
tools headers kvm: Sync kvm headers with the kernel sources
tools arch x86: Sync asm/cpufeatures.h with the kernel sources
tools headers x86: Sync disabled-features.h
tools include UAPI: Sync sound/asound.h copy
tools headers UAPI: Sync asm-generic/mman-common.h with the kernel
perf tools: Add arm64 version of get_cpuid()
tools headers UAPI: Sync drm/i915_drm.h with the kernel sources
tools headers uapi: Sync linux/fscrypt.h with the kernel sources
tools headers UAPI: Sync sched.h with the kernel
perf trace: Resolve prctl's 'option' arg strings to numbers
perf beauty prctl: Export the 'options' strarray
tools headers UAPI: Sync prctl.h with the kernel sources
tools headers UAPI: Sync copy of arm64's asm/unistd.h with the kernel sources
perf maps: Move kmap::kmaps setup to maps__insert()
perf maps: Fix map__clone() for struct kmap
perf maps: Mark ksymbol DSOs with kernel type
perf maps: Mark module DSOs with kernel type
tools include UAPI: Sync x86's syscalls_64.tbl, generic unistd.h and fcntl.h to pick up openat2 and pidfd_getfd
...
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The input_read function declares the size of the hex array relative to
sizeof(buf), but buf is a pointer argument of the function. The hex
array is meant to contain hexadecimal representation of the bin array.
Link: https://lore.kernel.org/r/20200215142130.22743-1-marek.behun@nic.cz
Fixes: 5bc7f990cd98 ("bus: Add support for Moxtet bus")
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reported-by: sohu0106 <sohu0106@126.com>
Signed-off-by: Olof Johansson <olof@lixom.net>
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If CONFIG_QFMT_V2 is not enabled, but CONFIG_QUOTA is enabled, when a
user tries to mount a file system with the quota or project quota
enabled, the kernel will emit a very confusing messsage:
EXT4-fs warning (device vdc): ext4_enable_quotas:5914: Failed to enable quota tracking (type=0, err=-3). Please run e2fsck to fix.
EXT4-fs (vdc): mount failed
We will now report an explanatory message indicating which kernel
configuration options have to be enabled, to avoid customer/sysadmin
confusion.
Link: https://lore.kernel.org/r/20200215012738.565735-1-tytso@mit.edu
Google-Bug-Id: 149093531
Fixes: 7c319d328505b778 ("ext4: make quota as first class supported feature")
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
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git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/urgent
Pull perf/urgent fixes from Arnaldo Carvalho de Melo:
BPF:
Arnaldo Carvalho de Melo:
- Fix script used to obtain kernel make directives to work with new kbuild
used for building BPF programs.
maps:
Jiri Olsa:
- Fixup kmap->kmaps backpointer in kernel maps.
arm64:
John Garry:
- Add arm64 version of get_cpuid() to get proper, arm64 specific output from
'perf list' and other tools.
perf top:
Kim Phillips:
- Update kernel idle symbols so that output in AMD systems is in line with
other systems.
perf stat:
Kim Phillips:
- Don't report a null stalled cycles per insn metric.
tools headers:
Arnaldo Carvalho de Melo:
- Sync tools/ headers with the kernel sources to get things like syscall
numbers and new arguments so that 'perf trace' can decode and use them in
tracepoint filters, e.g. prctl's new PR_{G,S}ET_IO_FLUSHER options.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200214172132.GA28389@embeddedor
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
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The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200214172022.GA27490@embeddedor
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
|
|
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200214171907.GA26588@embeddedor
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
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