diff options
| author | Vinayak Menon <vinmenon@codeaurora.org> | 2018-03-28 16:01:16 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-05-30 07:52:21 +0200 |
| commit | 28bbb0d963e06c76aeaf0f6b3f142b650d0e7a35 (patch) | |
| tree | 974d98c166bfbad2e4ab88f4734e0704f7d9d016 /mm | |
| parent | 08e9dbd5184e4e059adf1cc77b5dc08eca314a77 (diff) | |
mm/kmemleak.c: wait for scan completion before disabling free
[ Upstream commit 914b6dfff790544d9b77dfd1723adb3745ec9700 ]
A crash is observed when kmemleak_scan accesses the object->pointer,
likely due to the following race.
TASK A TASK B TASK C
kmemleak_write
(with "scan" and
NOT "scan=on")
kmemleak_scan()
create_object
kmem_cache_alloc fails
kmemleak_disable
kmemleak_do_cleanup
kmemleak_free_enabled = 0
kfree
kmemleak_free bails out
(kmemleak_free_enabled is 0)
slub frees object->pointer
update_checksum
crash - object->pointer
freed (DEBUG_PAGEALLOC)
kmemleak_do_cleanup waits for the scan thread to complete, but not for
direct call to kmemleak_scan via kmemleak_write. So add a wait for
kmemleak_scan completion before disabling kmemleak_free, and while at it
fix the comment on stop_scan_thread.
[vinmenon@codeaurora.org: fix stop_scan_thread comment]
Link: http://lkml.kernel.org/r/1522219972-22809-1-git-send-email-vinmenon@codeaurora.org
Link: http://lkml.kernel.org/r/1522063429-18992-1-git-send-email-vinmenon@codeaurora.org
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/kmemleak.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/mm/kmemleak.c b/mm/kmemleak.c index bd1374f402cd..d9e0be2a8189 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -1658,8 +1658,7 @@ static void start_scan_thread(void) } /* - * Stop the automatic memory scanning thread. This function must be called - * with the scan_mutex held. + * Stop the automatic memory scanning thread. */ static void stop_scan_thread(void) { @@ -1922,12 +1921,15 @@ static void kmemleak_do_cleanup(struct work_struct *work) { stop_scan_thread(); + mutex_lock(&scan_mutex); /* - * Once the scan thread has stopped, it is safe to no longer track - * object freeing. Ordering of the scan thread stopping and the memory - * accesses below is guaranteed by the kthread_stop() function. + * Once it is made sure that kmemleak_scan has stopped, it is safe to no + * longer track object freeing. Ordering of the scan thread stopping and + * the memory accesses below is guaranteed by the kthread_stop() + * function. */ kmemleak_free_enabled = 0; + mutex_unlock(&scan_mutex); if (!kmemleak_found_leaks) __kmemleak_do_cleanup(); |