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| author | Sudip Mukherjee <sudipm.mukherjee@gmail.com> | 2016-06-24 14:50:24 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-06-24 17:23:52 -0700 |
| commit | 8285027fc479949a7a166bc1b26ce57e894878a7 (patch) | |
| tree | 11874d42ed0637ce07ebc6f7739dfaa37bc12bd7 | |
| parent | 7c5b7239465932400ee0825bcc90624717c1af19 (diff) | |
| download | linux-8285027fc479949a7a166bc1b26ce57e894878a7.tar.bz2 | |
mm/page_owner: avoid null pointer dereference
We have dereferenced page_ext before checking it. Lets check it first
and then used it.
Fixes: f86e4271978b ("mm: check the return value of lookup_page_ext for all call sites")
Link: http://lkml.kernel.org/r/1465249059-7883-1-git-send-email-sudipm.mukherjee@gmail.com
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/page_owner.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/page_owner.c b/mm/page_owner.c index c6cda3e36212..fedeba88c9cb 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -207,13 +207,15 @@ void __dump_page_owner(struct page *page) .nr_entries = page_ext->nr_entries, .entries = &page_ext->trace_entries[0], }; - gfp_t gfp_mask = page_ext->gfp_mask; - int mt = gfpflags_to_migratetype(gfp_mask); + gfp_t gfp_mask; + int mt; if (unlikely(!page_ext)) { pr_alert("There is not page extension available.\n"); return; } + gfp_mask = page_ext->gfp_mask; + mt = gfpflags_to_migratetype(gfp_mask); if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) { pr_alert("page_owner info is not active (free page?)\n"); |