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| author | David Rientjes <rientjes@google.com> | 2016-09-01 16:15:07 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-09-01 17:52:01 -0700 |
| commit | c11600e4fed67ae4cd6a8096936afd445410e8ed (patch) | |
| tree | 0f71f8ca5028621c2615eb83699535fa8b0ffe84 /kernel | |
| parent | 19feeff18bbfde659baa58c2346f15a24d7c405e (diff) | |
| download | linux-0-day-c11600e4fed67ae4cd6a8096936afd445410e8ed.tar.gz linux-0-day-c11600e4fed67ae4cd6a8096936afd445410e8ed.tar.xz | |
mm, mempolicy: task->mempolicy must be NULL before dropping final reference
KASAN allocates memory from the page allocator as part of
kmem_cache_free(), and that can reference current->mempolicy through any
number of allocation functions. It needs to be NULL'd out before the
final reference is dropped to prevent a use-after-free bug:
BUG: KASAN: use-after-free in alloc_pages_current+0x363/0x370 at addr ffff88010b48102c
CPU: 0 PID: 15425 Comm: trinity-c2 Not tainted 4.8.0-rc2+ #140
...
Call Trace:
dump_stack
kasan_object_err
kasan_report_error
__asan_report_load2_noabort
alloc_pages_current <-- use after free
depot_save_stack
save_stack
kasan_slab_free
kmem_cache_free
__mpol_put <-- free
do_exit
This patch sets current->mempolicy to NULL before dropping the final
reference.
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1608301442180.63329@chino.kir.corp.google.com
Fixes: cd11016e5f52 ("mm, kasan: stackdepot implementation. Enable stackdepot for SLAB")
Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org> [4.6+]
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/exit.c | 7 |
1 files changed, 1 insertions, 6 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index 2f974ae042a67..091a78be3b09d 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -848,12 +848,7 @@ void do_exit(long code) TASKS_RCU(preempt_enable()); exit_notify(tsk, group_dead); proc_exit_connector(tsk); -#ifdef CONFIG_NUMA - task_lock(tsk); - mpol_put(tsk->mempolicy); - tsk->mempolicy = NULL; - task_unlock(tsk); -#endif + mpol_put_task_policy(tsk); #ifdef CONFIG_FUTEX if (unlikely(current->pi_state_cache)) kfree(current->pi_state_cache); |