| Age | Commit message (Collapse) | Author |
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The current message for telling the user that their compiler does not
support the counted_by attribute in the FAM_BOUNDS test does not make
much sense either grammatically or semantically. Fix it to make it
correct in both aspects.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20240321-lkdtm-improve-lack-of-counted_by-msg-v1-1-0fbf7481a29c@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
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In commit edb6538da3df ("lkdtm/bugs: Adjust lkdtm_HUNG_TASK() to avoid
tail call optimization") we marked lkdtm_HUNG_TASK() as
__noreturn. The compiler gets unhappy if it thinks a __noreturn
function might return, so there's a BUG_ON(1) at the end. Any human
can see that the function won't return and the compiler can figure
that out too. Except when it can't.
The MIPS architecture defines HAVE_ARCH_BUG_ON and defines its own
version of BUG_ON(). The MIPS version of BUG_ON() is not a macro but
is instead an inline function. Apparently this prevents the compiler
from realizing that the condition to BUG_ON() is constant and that the
function will never return.
Let's change the BUG_ON(1) to just BUG(), which it should have been to
begin with. The only reason I used BUG_ON(1) to begin with was because
I was used to using WARN_ON(1) when writing test code and WARN() and
BUG() are oddly inconsistent in this manner. :-/
Fixes: edb6538da3df ("lkdtm/bugs: Adjust lkdtm_HUNG_TASK() to avoid tail call optimization")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202401262204.wUFKRYZF-lkp@intel.com/
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20240126072852.1.Ib065e528a8620474a72f15baa2feead1f3d89865@changeid
Signed-off-by: Kees Cook <keescook@chromium.org>
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When testing with lkdtm_HUNG_TASK() and looking at the output, I
expected to see lkdtm_HUNG_TASK() in the stack crawl but it wasn't
there. Instead, the top function on at least some devices was
schedule() due to tail call optimization.
Let's do two things to help here:
1. We'll mark this as "__noreturn". On GCC at least this is documented
to prevent tail call optimization. The docs [1] say "In order to
preserve backtraces, GCC will never turn calls to noreturn
functions into tail calls."
2. We'll add a BUG_ON(1) at the end which means that schedule() is no
longer a tail call. Note that this is potentially important because
if we _did_ end up returning from schedule() due to some weird
issue then we'd potentially be violating the "noreturn" that we
told the compiler about. BUG is the right thing to do here.
[1] https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20240122164935.2.I26e8f68c312824fcc80c19d4e91de2d2bef958f0@changeid
Signed-off-by: Kees Cook <keescook@chromium.org>
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Upon a panic() the kernel will use either smp_send_stop() or
crash_smp_send_stop() to attempt to stop secondary CPUs via an IPI,
which may or may not be an NMI. Generally it's preferable that this is an
NMI so that CPUs can be stopped in as many situations as possible, but
it's not always possible to provide an NMI, and there are cases where
CPUs may be unable to handle the NMI regardless.
This patch adds a test for panic() where all other CPUs are stuck with
interrupts disabled, which can be used to check whether the kernel
gracefully handles CPUs failing to respond to a stop, and whether NMIs
actually work to stop CPUs.
For example, on arm64 *without* an NMI, this results in:
| # echo PANIC_STOP_IRQOFF > /sys/kernel/debug/provoke-crash/DIRECT
| lkdtm: Performing direct entry PANIC_STOP_IRQOFF
| Kernel panic - not syncing: panic stop irqoff test
| CPU: 2 PID: 24 Comm: migration/2 Not tainted 6.5.0-rc3-00077-ge6c782389895-dirty #4
| Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
| Stopper: multi_cpu_stop+0x0/0x1a0 <- stop_machine_cpuslocked+0x158/0x1a4
| Call trace:
| dump_backtrace+0x94/0xec
| show_stack+0x18/0x24
| dump_stack_lvl+0x74/0xc0
| dump_stack+0x18/0x24
| panic+0x358/0x3e8
| lkdtm_PANIC+0x0/0x18
| multi_cpu_stop+0x9c/0x1a0
| cpu_stopper_thread+0x84/0x118
| smpboot_thread_fn+0x224/0x248
| kthread+0x114/0x118
| ret_from_fork+0x10/0x20
| SMP: stopping secondary CPUs
| SMP: failed to stop secondary CPUs 0-3
| Kernel Offset: 0x401cf3490000 from 0xffff80008000000c0
| PHYS_OFFSET: 0x40000000
| CPU features: 0x00000000,68c167a1,cce6773f
| Memory Limit: none
| ---[ end Kernel panic - not syncing: panic stop irqoff test ]---
Note the "failed to stop secondary CPUs 0-3" message.
On arm64 *with* an NMI, this results in:
| # echo PANIC_STOP_IRQOFF > /sys/kernel/debug/provoke-crash/DIRECT
| lkdtm: Performing direct entry PANIC_STOP_IRQOFF
| Kernel panic - not syncing: panic stop irqoff test
| CPU: 1 PID: 19 Comm: migration/1 Not tainted 6.5.0-rc3-00077-ge6c782389895-dirty #4
| Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
| Stopper: multi_cpu_stop+0x0/0x1a0 <- stop_machine_cpuslocked+0x158/0x1a4
| Call trace:
| dump_backtrace+0x94/0xec
| show_stack+0x18/0x24
| dump_stack_lvl+0x74/0xc0
| dump_stack+0x18/0x24
| panic+0x358/0x3e8
| lkdtm_PANIC+0x0/0x18
| multi_cpu_stop+0x9c/0x1a0
| cpu_stopper_thread+0x84/0x118
| smpboot_thread_fn+0x224/0x248
| kthread+0x114/0x118
| ret_from_fork+0x10/0x20
| SMP: stopping secondary CPUs
| Kernel Offset: 0x55a9c0bc0000 from 0xffff800080000000
| PHYS_OFFSET: 0x40000000
| CPU features: 0x00000000,68c167a1,fce6773f
| Memory Limit: none
| ---[ end Kernel panic - not syncing: panic stop irqoff test ]---
Note the absence of a "failed to stop secondary CPUs" message, since we
don't log anything when secondary CPUs are successfully stopped.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20230921161634.4063233-1-mark.rutland@arm.com
Signed-off-by: Kees Cook <keescook@chromium.org>
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Add new CONFIG_UBSAN_BOUNDS test for __counted_by attribute.
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
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Numerous production kernel configs (see [1, 2]) are choosing to enable
CONFIG_DEBUG_LIST, which is also being recommended by KSPP for hardened
configs [3]. The motivation behind this is that the option can be used
as a security hardening feature (e.g. CVE-2019-2215 and CVE-2019-2025
are mitigated by the option [4]).
The feature has never been designed with performance in mind, yet common
list manipulation is happening across hot paths all over the kernel.
Introduce CONFIG_LIST_HARDENED, which performs list pointer checking
inline, and only upon list corruption calls the reporting slow path.
To generate optimal machine code with CONFIG_LIST_HARDENED:
1. Elide checking for pointer values which upon dereference would
result in an immediate access fault (i.e. minimal hardening
checks). The trade-off is lower-quality error reports.
2. Use the __preserve_most function attribute (available with Clang,
but not yet with GCC) to minimize the code footprint for calling
the reporting slow path. As a result, function size of callers is
reduced by avoiding saving registers before calling the rarely
called reporting slow path.
Note that all TUs in lib/Makefile already disable function tracing,
including list_debug.c, and __preserve_most's implied notrace has
no effect in this case.
3. Because the inline checks are a subset of the full set of checks in
__list_*_valid_or_report(), always return false if the inline
checks failed. This avoids redundant compare and conditional
branch right after return from the slow path.
As a side-effect of the checks being inline, if the compiler can prove
some condition to always be true, it can completely elide some checks.
Since DEBUG_LIST is functionally a superset of LIST_HARDENED, the
Kconfig variables are changed to reflect that: DEBUG_LIST selects
LIST_HARDENED, whereas LIST_HARDENED itself has no dependency on
DEBUG_LIST.
Running netperf with CONFIG_LIST_HARDENED (using a Clang compiler with
"preserve_most") shows throughput improvements, in my case of ~7% on
average (up to 20-30% on some test cases).
Link: https://r.android.com/1266735 [1]
Link: https://gitlab.archlinux.org/archlinux/packaging/packages/linux/-/blob/main/config [2]
Link: https://kernsec.org/wiki/index.php/Kernel_Self_Protection_Project/Recommended_Settings [3]
Link: https://googleprojectzero.blogspot.com/2019/11/bad-binder-android-in-wild-exploit.html [4]
Signed-off-by: Marco Elver <elver@google.com>
Link: https://lore.kernel.org/r/20230811151847.1594958-3-elver@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull hardening updates from Kees Cook:
"There are three areas of note:
A bunch of strlcpy()->strscpy() conversions ended up living in my tree
since they were either Acked by maintainers for me to carry, or got
ignored for multiple weeks (and were trivial changes).
The compiler option '-fstrict-flex-arrays=3' has been enabled
globally, and has been in -next for the entire devel cycle. This
changes compiler diagnostics (though mainly just -Warray-bounds which
is disabled) and potential UBSAN_BOUNDS and FORTIFY _warning_
coverage. In other words, there are no new restrictions, just
potentially new warnings. Any new FORTIFY warnings we've seen have
been fixed (usually in their respective subsystem trees). For more
details, see commit df8fc4e934c12b.
The under-development compiler attribute __counted_by has been added
so that we can start annotating flexible array members with their
associated structure member that tracks the count of flexible array
elements at run-time. It is possible (likely?) that the exact syntax
of the attribute will change before it is finalized, but GCC and Clang
are working together to sort it out. Any changes can be made to the
macro while we continue to add annotations.
As an example of that last case, I have a treewide commit waiting with
such annotations found via Coccinelle:
https://git.kernel.org/linus/adc5b3cb48a049563dc673f348eab7b6beba8a9b
Also see commit dd06e72e68bcb4 for more details.
Summary:
- Fix KMSAN vs FORTIFY in strlcpy/strlcat (Alexander Potapenko)
- Convert strreplace() to return string start (Andy Shevchenko)
- Flexible array conversions (Arnd Bergmann, Wyes Karny, Kees Cook)
- Add missing function prototypes seen with W=1 (Arnd Bergmann)
- Fix strscpy() kerndoc typo (Arne Welzel)
- Replace strlcpy() with strscpy() across many subsystems which were
either Acked by respective maintainers or were trivial changes that
went ignored for multiple weeks (Azeem Shaikh)
- Remove unneeded cc-option test for UBSAN_TRAP (Nick Desaulniers)
- Add KUnit tests for strcat()-family
- Enable KUnit tests of FORTIFY wrappers under UML
- Add more complete FORTIFY protections for strlcat()
- Add missed disabling of FORTIFY for all arch purgatories.
- Enable -fstrict-flex-arrays=3 globally
- Tightening UBSAN_BOUNDS when using GCC
- Improve checkpatch to check for strcpy, strncpy, and fake flex
arrays
- Improve use of const variables in FORTIFY
- Add requested struct_size_t() helper for types not pointers
- Add __counted_by macro for annotating flexible array size members"
* tag 'hardening-v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (54 commits)
netfilter: ipset: Replace strlcpy with strscpy
uml: Replace strlcpy with strscpy
um: Use HOST_DIR for mrproper
kallsyms: Replace all non-returning strlcpy with strscpy
sh: Replace all non-returning strlcpy with strscpy
of/flattree: Replace all non-returning strlcpy with strscpy
sparc64: Replace all non-returning strlcpy with strscpy
Hexagon: Replace all non-returning strlcpy with strscpy
kobject: Use return value of strreplace()
lib/string_helpers: Change returned value of the strreplace()
jbd2: Avoid printing outside the boundary of the buffer
checkpatch: Check for 0-length and 1-element arrays
riscv/purgatory: Do not use fortified string functions
s390/purgatory: Do not use fortified string functions
x86/purgatory: Do not use fortified string functions
acpi: Replace struct acpi_table_slit 1-element array with flex-array
clocksource: Replace all non-returning strlcpy with strscpy
string: use __builtin_memcpy() in strlcpy/strlcat
staging: most: Replace all non-returning strlcpy with strscpy
drm/i2c: tda998x: Replace all non-returning strlcpy with strscpy
...
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For certain configs objtool will complain like:
vmlinux.o: warning: objtool: lkdtm_UNSET_SMEP+0x1c3: relocation to !ENDBR: native_write_cr4+0x41
What happens is that GCC optimizes the loop:
insn = (unsigned char *)native_write_cr4;
for (i = 0; i < MOV_CR4_DEPTH; i++)
to read something like:
for (insn = (unsigned char *)native_write_cr4;
insn < (unsigned char *)native_write_cr4 + MOV_CR4_DEPTH;
insn++)
Which then obviously generates the text reference
native_write_cr4+041. Since none of this is a fast path, simply
confuse GCC enough to inhibit this optimization.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/Y3JdgbXRV0MNZ+9h@hirez.programming.kicks-ass.net
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
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The testing for ARRAY_BOUNDS just wants an uninstrumented array,
and the proper flexible array definition is fine for that.
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Bill Wendling <morbo@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
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When building with Clang we encounter the following warning
(ARCH=hexagon + CONFIG_FRAME_WARN=0):
| ../drivers/misc/lkdtm/bugs.c:107:3: error: format specifies type
| 'unsigned long' but the argument has type 'int' [-Werror,-Wformat]
| REC_STACK_SIZE, recur_count);
| ^~~~~~~~~~~~~~
Cast REC_STACK_SIZE to `unsigned long` to match format specifier `%lu`
as well as maintain symmetry with `#define REC_STACK_SIZE
(_AC(CONFIG_FRAME_WARN, UL) / 2)`.
Link: https://github.com/ClangBuiltLinux/linux/issues/378
Reported-by: Nathan Chancellor <nathan@kernel.org>
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Fixes: 24cccab42c419 ("lkdtm/bugs: Adjust recursion test to avoid elision")
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220721215706.4153027-1-justinstitt@google.com
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It's long been annoying that to add a new LKDTM test one had to update
lkdtm.h and core.c to get it "registered". Switch to a per-category
list and update the crashtype walking code in core.c to handle it.
This also means that all the lkdtm_* tests themselves can be static now.
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
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When you don't select CONFIG_UBSAN_TRAP, you get:
# echo ARRAY_BOUNDS > /sys/kernel/debug/provoke-crash/DIRECT
[ 102.265827] ================================================================================
[ 102.278433] UBSAN: array-index-out-of-bounds in drivers/misc/lkdtm/bugs.c:342:16
[ 102.287207] index 8 is out of range for type 'char [8]'
[ 102.298722] ================================================================================
[ 102.313712] lkdtm: FAIL: survived array bounds overflow!
[ 102.318770] lkdtm: Unexpected! This kernel (5.16.0-rc1-s3k-dev-01884-g720dcf79314a ppc) was built with CONFIG_UBSAN_BOUNDS=y
It is not correct because when CONFIG_UBSAN_TRAP is not selected
you can't expect array bounds overflow to kill the thread.
Modify the logic so that when the kernel is built with
CONFIG_UBSAN_BOUNDS but without CONFIG_UBSAN_TRAP, you get a warning
about CONFIG_UBSAN_TRAP not been selected instead.
This also require a fix of pr_expected_config(), otherwise the
following error is encountered.
CC drivers/misc/lkdtm/bugs.o
drivers/misc/lkdtm/bugs.c: In function 'lkdtm_ARRAY_BOUNDS':
drivers/misc/lkdtm/bugs.c:351:2: error: 'else' without a previous 'if'
351 | else
| ^~~~
Fixes: c75be56e35b2 ("lkdtm/bugs: Add ARRAY_BOUNDS to selftests")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/363b58690e907c677252467a94fe49444c80ea76.1649704381.git.christophe.leroy@csgroup.eu
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As the possible failure of the kmalloc(), the not_checked and checked
could be NULL pointer.
Therefore, it should be better to check it in order to avoid the
dereference of the NULL pointer.
Also, we need to kfree the 'not_checked' and 'checked' to avoid
the memory leak if fails.
And since it is just a test, it may directly return without error
number.
Fixes: ae2e1aad3e48 ("drivers/misc/lkdtm/bugs.c: add arithmetic overflow and array bounds checks")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Acked-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220120092936.1874264-1-jiasheng@iscas.ac.cn
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The recursive_loop() function is intended as a diagnostic to ensure that
exhausting the stack is caught and mitigated. Currently, it uses
pr_info() to ensure that the function has side effects that the compiler
cannot simply optimize away, so that the stack footprint does not get
reduced inadvertently.
The typical mitigation for stack overflow is to kill the task, and this
overflow may occur inside the call to pr_info(), which means it could be
holding the console lock when this happens. This means that the console
lock is never going to be released again, preventing the diagnostic
prints related to the stack overflow handling from being visible on the
console.
So let's replace the call to pr_info() with a call to
memzero_explicit(), which is not a 'magic' function name like memset()
or memcpy(), which the compiler may replace with plain loads and stores.
To ensure that the stack frames are nested rather than tail-called, put
the call to memzero_explicit() after the recursive call.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20211007081235.382697-1-ardb@kernel.org
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Introduce REPORT_STACK_CANARY to check for differing stack canaries
between two processes (i.e. that an architecture is correctly implementing
per-task stack canaries), using the task_struct canary as the hint to
locate in the stack. Requires that one of the processes being tested
not be pid 1.
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20211022223826.330653-3-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The FORTIFY_SOURCE tests were split between bugs.c and fortify.c. Move
tests into fortify.c, standardize their naming, add CONFIG hints, and
add them to the lkdtm selftests.
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210818174855.2307828-3-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Add CONFIG hints about why the ARRAY_BOUNDS test might fail, and
similarly include the CONFIGs needed to pass the ARRAY_BOUNDS test via
the selftests, and add to selftests.
Cc: kernelci@groups.io
Suggested-by: Guillaume Tucker <guillaume.tucker@collabora.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210818174855.2307828-2-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char / misc driver updates from Greg KH:
"Here is the big set of char / misc and other driver subsystem updates
for 5.14-rc1. Included in here are:
- habanalabs driver updates
- fsl-mc driver updates
- comedi driver updates
- fpga driver updates
- extcon driver updates
- interconnect driver updates
- mei driver updates
- nvmem driver updates
- phy driver updates
- pnp driver updates
- soundwire driver updates
- lots of other tiny driver updates for char and misc drivers
This is looking more and more like the "various driver subsystems
mushed together" tree...
All of these have been in linux-next for a while with no reported
issues"
* tag 'char-misc-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (292 commits)
mcb: Use DEFINE_RES_MEM() helper macro and fix the end address
PNP: moved EXPORT_SYMBOL so that it immediately followed its function/variable
bus: mhi: pci-generic: Add missing 'pci_disable_pcie_error_reporting()' calls
bus: mhi: Wait for M2 state during system resume
bus: mhi: core: Fix power down latency
intel_th: Wait until port is in reset before programming it
intel_th: msu: Make contiguous buffers uncached
intel_th: Remove an unused exit point from intel_th_remove()
stm class: Spelling fix
nitro_enclaves: Set Bus Master for the NE PCI device
misc: ibmasm: Modify matricies to matrices
misc: vmw_vmci: return the correct errno code
siox: Simplify error handling via dev_err_probe()
fpga: machxo2-spi: Address warning about unused variable
lkdtm/heap: Add init_on_alloc tests
selftests/lkdtm: Enable various testable CONFIGs
lkdtm: Add CONFIG hints in errors where possible
lkdtm: Enable DOUBLE_FAULT on all architectures
lkdtm/heap: Add vmalloc linear overflow test
lkdtm/bugs: XFAIL UNALIGNED_LOAD_STORE_WRITE
...
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For various failure conditions, try to include some details about where
to look for reasons about the failure.
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210623203936.3151093-8-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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When built under CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, this test is
expected to fail (i.e. not trip an exception).
Fixes: 46d1a0f03d66 ("selftests/lkdtm: Add tests for LKDTM targets")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210623203936.3151093-5-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This patch add the ARM64_PTR_AUTH_KERNEL config and deals with the
build aspect of it.
Userspace support has no dependency on the toolchain therefore all
toolchain checks and build flags are controlled the new config
option.
The default config behavior will not be changed.
Signed-off-by: Daniel Kiss <daniel.kiss@arm.com>
Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210613092632.93591-2-daniel.kiss@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
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For validating the stack offset behavior, report the offset from a given
process's first seen stack address. Add s script to calculate the results
to the LKDTM kselftests.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210401232347.2791257-7-keescook@chromium.org
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Add code to test both:
- runtime detection of the overrun of a structure. This covers the
__builtin_object_size(x, 0) case. This test is called FORTIFY_OBJECT.
- runtime detection of the overrun of a char array within a structure.
This covers the __builtin_object_size(x, 1) case which can be used
for some string functions. This test is called FORTIFY_SUBOBJECT.
Link: https://lkml.kernel.org/r/20201122162451.27551-3-laniel_francis@privacyrequired.com
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Francis Laniel <laniel_francis@privacyrequired.com>
Suggested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Daniel Micay <danielmicay@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Once we can't manipulate the address limit, we also can't test what
happens when the manipulation is abused.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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The result may not be intereresting, but not using a set variable
is bad form and causes W=1 kernel builds to complain.
Fixes the following W=1 warning(s):
drivers/misc/lkdtm/bugs.c: In function ‘lkdtm_STACK_GUARD_PAGE_LEADING’:
drivers/misc/lkdtm/bugs.c:331:25: warning: variable ‘byte’ set but not used [-Wunused-but-set-variable]
331 | volatile unsigned char byte;
| ^~~~
drivers/misc/lkdtm/bugs.c: In function ‘lkdtm_STACK_GUARD_PAGE_TRAILING’:
drivers/misc/lkdtm/bugs.c:345:25: warning: variable ‘byte’ set but not used [-Wunused-but-set-variable]
345 | volatile unsigned char byte;
| ^~~~
Cc: Kees Cook <keescook@chromium.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20200626130525.389469-5-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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I'd like arch-specific tests to XFAIL when on a mismatched architecture
so that we can more easily compare test coverage across all systems.
Lacking kernel configs or CPU features count as a FAIL, not an XFAIL.
Additionally fixes a build failure under 32-bit UML.
Fixes: b09511c253e5 ("lkdtm: Add a DOUBLE_FAULT crash type on x86")
Fixes: cea23efb4de2 ("lkdtm/bugs: Make double-fault test always available")
Fixes: 6cb6982f42cb ("lkdtm: arm64: test kernel pointer authentication")
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200625203704.317097-5-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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It seems at least Clang is able to throw away writes it knows are
destined for read-only memory, which makes things like the WRITE_RO test
fail, as the write gets elided. Instead, force the variable to be
volatile, and make similar changes through-out other tests in an effort
to avoid needing to repeat fixing these kinds of problems. Also includes
pr_err() calls in failure paths so that kernel logs are more clear in
the failure case.
Reported-by: Prasad Sodagudi <psodagud@codeaurora.org>
Suggested-by: Sami Tolvanen <samitolvanen@google.com>
Fixes: 9ae113ce5faf ("lkdtm: add tests for additional page permissions")
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200625203704.317097-2-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Fix spelling mistake s/Intentially/Intentionally
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200401182855.GA16253@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Adds LKDTM tests for arithmetic overflow (both signed and unsigned), as
well as array bounds checking.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Elena Petrova <lenaptr@google.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Link: http://lkml.kernel.org/r/20200227193516.32566-4-keescook@chromium.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This test is specific for arm64. When in-kernel Pointer Authentication
config is enabled, the return address stored in the stack is signed.
This feature helps in ROP kind of attack. If any parameters used to
generate the pac (<key, sp, lr>) is modified then this will fail in
the authentication stage and will lead to abort.
This test changes the input parameter APIA kernel keys to cause abort.
The pac computed from the new key can be same as last due to hash
collision so this is retried for few times as there is no reliable way
to compare the pacs. Even though this test may fail even after retries
but this may cause authentication failure at a later stage in earlier
function returns.
This test can be invoked as,
echo CORRUPT_PAC > /sys/kernel/debug/provoke-crash/DIRECT
or as below if inserted as a module,
insmod lkdtm.ko cpoint_name=DIRECT cpoint_type=CORRUPT_PAC cpoint_count=1
[ 13.118166] lkdtm: Performing direct entry CORRUPT_PAC
[ 13.118298] lkdtm: Clearing PAC from the return address
[ 13.118466] Unable to handle kernel paging request at virtual address bfff8000108648ec
[ 13.118626] Mem abort info:
[ 13.118666] ESR = 0x86000004
[ 13.118866] EC = 0x21: IABT (current EL), IL = 32 bits
[ 13.118966] SET = 0, FnV = 0
[ 13.119117] EA = 0, S1PTW = 0
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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When building ARCH=um with CONFIG_UML_X86=y and CONFIG_64BIT=y we get
the build errors:
drivers/misc/lkdtm/bugs.c: In function ‘lkdtm_UNSET_SMEP’:
drivers/misc/lkdtm/bugs.c:288:8: error: implicit declaration of function ‘native_read_cr4’ [-Werror=implicit-function-declaration]
cr4 = native_read_cr4();
^~~~~~~~~~~~~~~
drivers/misc/lkdtm/bugs.c:290:13: error: ‘X86_CR4_SMEP’ undeclared (first use in this function); did you mean ‘X86_FEATURE_SMEP’?
if ((cr4 & X86_CR4_SMEP) != X86_CR4_SMEP) {
^~~~~~~~~~~~
X86_FEATURE_SMEP
drivers/misc/lkdtm/bugs.c:290:13: note: each undeclared identifier is reported only once for each function it appears in
drivers/misc/lkdtm/bugs.c:297:2: error: implicit declaration of function ‘native_write_cr4’; did you mean ‘direct_write_cr4’? [-Werror=implicit-function-declaration]
native_write_cr4(cr4);
^~~~~~~~~~~~~~~~
direct_write_cr4
So specify that this block of code should only build when
CONFIG_X86_64=y *AND* CONFIG_UML is unset.
Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20191213003522.66450-1-brendanhiggins@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Adjust the DOUBLE_FAULT test to always be available (so test harnesses
don't have to make exceptions more missing tests), and for the
arch-specific tests to "XFAIL" so that test harnesses can reason about
expected vs unexpected failures.
Fixes: b09511c253e5 ("lkdtm: Add a DOUBLE_FAULT crash type on x86")
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/202001021226.751D3F869D@keescook
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The DOUBLE_FAULT crash does INT $8, which is a decent approximation
of a double fault. This is useful for testing the double fault
handling. Use it like:
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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We need the fixes in here as well for testing and merges
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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lkdtm/bugs.c:94:2: error: format '%d' expects argument of type 'int', but argument 2 has type 'long unsigned int' [-Werror=format=]
pr_info("Calling function with %d frame size to depth %d ...\n",
^
THREAD_SIZE is defined as a unsigned long, cast CONFIG_FRAME_WARN to
unsigned long as well.
Fixes: 24cccab42c419 ("lkdtm/bugs: Adjust recursion test to avoid elision")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Acked-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20190827173619.170065-1-rrangel@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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There are three paths through the kernel code exception logging:
- BUG (no configurable printk message)
- WARN_ON (no configurable printk message)
- WARN (configurable printk message)
LKDTM was not testing WARN_ON(). This is needed to evaluate the placement
of the "cut here" line, which needs special handling in each of the
three exceptions (and between architectures that implement instruction
exceptions to implement the code exceptions).
Signed-off-by: Kees Cook <keescook@chromium.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char / misc driver updates from Greg KH:
"Here is the "large" pull request for char and misc and other assorted
smaller driver subsystems for 5.3-rc1.
It seems that this tree is becoming the funnel point of lots of
smaller driver subsystems, which is fine for me, but that's why it is
getting larger over time and does not just contain stuff under
drivers/char/ and drivers/misc.
Lots of small updates all over the place here from different driver
subsystems:
- habana driver updates
- coresight driver updates
- documentation file movements and updates
- Android binder fixes and updates
- extcon driver updates
- google firmware driver updates
- fsi driver updates
- smaller misc and char driver updates
- soundwire driver updates
- nvmem driver updates
- w1 driver fixes
All of these have been in linux-next for a while with no reported
issues"
* tag 'char-misc-5.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (188 commits)
coresight: Do not default to CPU0 for missing CPU phandle
dt-bindings: coresight: Change CPU phandle to required property
ocxl: Allow contexts to be attached with a NULL mm
fsi: sbefifo: Don't fail operations when in SBE IPL state
coresight: tmc: Smatch: Fix potential NULL pointer dereference
coresight: etm3x: Smatch: Fix potential NULL pointer dereference
coresight: Potential uninitialized variable in probe()
coresight: etb10: Do not call smp_processor_id from preemptible
coresight: tmc-etf: Do not call smp_processor_id from preemptible
coresight: tmc-etr: alloc_perf_buf: Do not call smp_processor_id from preemptible
coresight: tmc-etr: Do not call smp_processor_id() from preemptible
docs: misc-devices: convert files without extension to ReST
fpga: dfl: fme: align PR buffer size per PR datawidth
fpga: dfl: fme: remove copy_to_user() in ioctl for PR
fpga: dfl-fme-mgr: fix FME_PR_INTFC_ID register address.
intel_th: msu: Start read iterator from a non-empty window
intel_th: msu: Split sgt array and pointer in multiwindow mode
intel_th: msu: Support multipage blocks
intel_th: pci: Add Ice Lake NNPI support
intel_th: msu: Fix single mode with disabled IOMMU
...
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git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull force_sig() argument change from Eric Biederman:
"A source of error over the years has been that force_sig has taken a
task parameter when it is only safe to use force_sig with the current
task.
The force_sig function is built for delivering synchronous signals
such as SIGSEGV where the userspace application caused a synchronous
fault (such as a page fault) and the kernel responded with a signal.
Because the name force_sig does not make this clear, and because the
force_sig takes a task parameter the function force_sig has been
abused for sending other kinds of signals over the years. Slowly those
have been fixed when the oopses have been tracked down.
This set of changes fixes the remaining abusers of force_sig and
carefully rips out the task parameter from force_sig and friends
making this kind of error almost impossible in the future"
* 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (27 commits)
signal/x86: Move tsk inside of CONFIG_MEMORY_FAILURE in do_sigbus
signal: Remove the signal number and task parameters from force_sig_info
signal: Factor force_sig_info_to_task out of force_sig_info
signal: Generate the siginfo in force_sig
signal: Move the computation of force into send_signal and correct it.
signal: Properly set TRACE_SIGNAL_LOSE_INFO in __send_signal
signal: Remove the task parameter from force_sig_fault
signal: Use force_sig_fault_to_task for the two calls that don't deliver to current
signal: Explicitly call force_sig_fault on current
signal/unicore32: Remove tsk parameter from __do_user_fault
signal/arm: Remove tsk parameter from __do_user_fault
signal/arm: Remove tsk parameter from ptrace_break
signal/nds32: Remove tsk parameter from send_sigtrap
signal/riscv: Remove tsk parameter from do_trap
signal/sh: Remove tsk parameter from force_sig_info_fault
signal/um: Remove task parameter from send_sigtrap
signal/x86: Remove task parameter from send_sigtrap
signal: Remove task parameter from force_sig_mceerr
signal: Remove task parameter from force_sig
signal: Remove task parameter from force_sigsegv
...
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This adds an x86-specific test for pinned cr4 bits. A successful test
will validate pinning and check the ROP-style call-middle-of-function
defense, if needed. For example, in the case of native_write_cr4()
looking like this:
ffffffff8171bce0 <native_write_cr4>:
ffffffff8171bce0: 48 8b 35 79 46 f2 00 mov 0xf24679(%rip),%rsi
ffffffff8171bce7: 48 09 f7 or %rsi,%rdi
ffffffff8171bcea: 0f 22 e7 mov %rdi,%cr4
...
ffffffff8171bd5a: c3 retq
The UNSET_SMEP test will jump to ffffffff8171bcea (the mov to cr4)
instead of ffffffff8171bce0 (native_write_cr4() entry) to simulate a
direct-call bypass attempt.
Expected successful results:
# echo UNSET_SMEP > /sys/kernel/debug/provoke-crash/DIRECT
# dmesg
[ 79.594433] lkdtm: Performing direct entry UNSET_SMEP
[ 79.596459] lkdtm: trying to clear SMEP normally
[ 79.598406] lkdtm: ok: SMEP did not get cleared
[ 79.599981] lkdtm: trying to clear SMEP with call gadget
[ 79.601810] ------------[ cut here ]------------
[ 79.603421] Attempt to unpin cr4 bits: 100000; bypass attack?!
...
[ 79.650170] ---[ end trace 2452ca0f6126242e ]---
[ 79.650937] lkdtm: ok: SMEP removal was reverted
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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All of the remaining callers pass current into force_sig so
remove the task parameter to make this obvious and to make
misuse more difficult in the future.
This also makes it clear force_sig passes current into force_sig_info.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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While I was able to trick gcc into keeping a pathological recursion,
Clang was not so easily fooled. Instead, switch to using "volatile" and
side-effects to keep the stack variable allocated and to run the function.
Additionally renames "OVERFLOW" to "EXHAUST_STACK" to better describe the
test.
Signed-off-by: Kees Cook <keescook@chromium.org>
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The LKDTM modules keep expanding, and it's getting weird to have each file
get a prefix. Instead, move to a subdirectory for cleaner handling.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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