diff options
| author | Andrey Ryabinin <aryabinin@virtuozzo.com> | 2019-04-25 22:23:58 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-16 19:40:26 +0200 |
| commit | 073d8f286f34b50058ad8c3929a4421f4b0e449f (patch) | |
| tree | 4643a4356821eca014aa6ffe29d7c4f7b57877dc | |
| parent | 61fadd8a5000780622ed647a39ab26cae480b365 (diff) | |
mm/page_alloc.c: avoid potential NULL pointer dereference
[ Upstream commit 8139ad043d632c0e9e12d760068a7a8e91659aa1 ]
ac.preferred_zoneref->zone passed to alloc_flags_nofragment() can be NULL.
'zone' pointer unconditionally derefernced in alloc_flags_nofragment().
Bail out on NULL zone to avoid potential crash. Currently we don't see
any crashes only because alloc_flags_nofragment() has another bug which
allows compiler to optimize away all accesses to 'zone'.
Link: http://lkml.kernel.org/r/20190423120806.3503-1-aryabinin@virtuozzo.com
Fixes: 6bb154504f8b ("mm, page_alloc: spread allocations across zones before introducing fragmentation")
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | mm/page_alloc.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index eedb57f9b40b..d59be95ba45c 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3385,6 +3385,9 @@ alloc_flags_nofragment(struct zone *zone, gfp_t gfp_mask) alloc_flags |= ALLOC_KSWAPD; #ifdef CONFIG_ZONE_DMA32 + if (!zone) + return alloc_flags; + if (zone_idx(zone) != ZONE_NORMAL) goto out; |