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authorAndy Lutomirski <luto@amacapital.net>2015-02-12 15:01:14 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-12 18:54:12 -0800
commitf56141e3e2d9aabf7e6b89680ab572c2cdbb2a24 (patch)
tree481e3d99bc1121ce75d505d340153b9d158e60c5 /kernel
parentedc924e023ae2022fc29f1246e115c610c9abf38 (diff)
all arches, signal: move restart_block to struct task_struct
If an attacker can cause a controlled kernel stack overflow, overwriting the restart block is a very juicy exploit target. This is because the restart_block is held in the same memory allocation as the kernel stack. Moving the restart block to struct task_struct prevents this exploit by making the restart_block harder to locate. Note that there are other fields in thread_info that are also easy targets, at least on some architectures. It's also a decent simplification, since the restart code is more or less identical on all architectures. [james.hogan@imgtec.com: metag: align thread_info::supervisor_stack] Signed-off-by: Andy Lutomirski <luto@amacapital.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: David Miller <davem@davemloft.net> Acked-by: Richard Weinberger <richard@nod.at> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no> Cc: Steven Miao <realmz6@gmail.com> Cc: Mark Salter <msalter@redhat.com> Cc: Aurelien Jacquiot <a-jacquiot@ti.com> Cc: Mikael Starvik <starvik@axis.com> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Cc: David Howells <dhowells@redhat.com> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Michal Simek <monstr@monstr.eu> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Jonas Bonn <jonas@southpole.se> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Chen Liqin <liqin.linux@gmail.com> Cc: Lennox Wu <lennox.wu@gmail.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: Chris Zankel <chris@zankel.net> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Guenter Roeck <linux@roeck-us.net> Signed-off-by: James Hogan <james.hogan@imgtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/compat.c5
-rw-r--r--kernel/futex.c2
-rw-r--r--kernel/signal.c2
-rw-r--r--kernel/time/alarmtimer.c2
-rw-r--r--kernel/time/hrtimer.c2
-rw-r--r--kernel/time/posix-cpu-timers.c3
6 files changed, 7 insertions, 9 deletions
diff --git a/kernel/compat.c b/kernel/compat.c
index ebb3c369d03d..24f00610c575 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -276,8 +276,7 @@ COMPAT_SYSCALL_DEFINE2(nanosleep, struct compat_timespec __user *, rqtp,
* core implementation decides to return random nonsense.
*/
if (ret == -ERESTART_RESTARTBLOCK) {
- struct restart_block *restart
- = &current_thread_info()->restart_block;
+ struct restart_block *restart = &current->restart_block;
restart->fn = compat_nanosleep_restart;
restart->nanosleep.compat_rmtp = rmtp;
@@ -860,7 +859,7 @@ COMPAT_SYSCALL_DEFINE4(clock_nanosleep, clockid_t, which_clock, int, flags,
return -EFAULT;
if (err == -ERESTART_RESTARTBLOCK) {
- restart = &current_thread_info()->restart_block;
+ restart = &current->restart_block;
restart->fn = compat_clock_nanosleep_restart;
restart->nanosleep.compat_rmtp = rmtp;
}
diff --git a/kernel/futex.c b/kernel/futex.c
index 4eeb63de7e54..2a5e3830e953 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2217,7 +2217,7 @@ retry:
if (!abs_time)
goto out;
- restart = &current_thread_info()->restart_block;
+ restart = &current->restart_block;
restart->fn = futex_wait_restart;
restart->futex.uaddr = uaddr;
restart->futex.val = val;
diff --git a/kernel/signal.c b/kernel/signal.c
index 16a305295256..33a52759cc0e 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2501,7 +2501,7 @@ EXPORT_SYMBOL(unblock_all_signals);
*/
SYSCALL_DEFINE0(restart_syscall)
{
- struct restart_block *restart = &current_thread_info()->restart_block;
+ struct restart_block *restart = &current->restart_block;
return restart->fn(restart);
}
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index a7077d3ae52f..1b001ed1edb9 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -788,7 +788,7 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
goto out;
}
- restart = &current_thread_info()->restart_block;
+ restart = &current->restart_block;
restart->fn = alarm_timer_nsleep_restart;
restart->nanosleep.clockid = type;
restart->nanosleep.expires = exp.tv64;
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 3f5e183c3d97..bee0c1f78091 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1583,7 +1583,7 @@ long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
goto out;
}
- restart = &current_thread_info()->restart_block;
+ restart = &current->restart_block;
restart->fn = hrtimer_nanosleep_restart;
restart->nanosleep.clockid = t.timer.base->clockid;
restart->nanosleep.rmtp = rmtp;
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index a16b67859e2a..0075da74abf0 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1334,8 +1334,7 @@ static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
struct timespec *rqtp, struct timespec __user *rmtp)
{
- struct restart_block *restart_block =
- &current_thread_info()->restart_block;
+ struct restart_block *restart_block = &current->restart_block;
struct itimerspec it;
int error;