summaryrefslogtreecommitdiff
path: root/mm/page_alloc.c
diff options
context:
space:
mode:
authorMaurizio Lombardi <mlombard@redhat.com>2022-07-15 15:50:13 +0300
committerAndrew Morton <akpm@linux-foundation.org>2022-09-26 22:14:34 +0300
commitdac22531bbd4af2426c4e29e05594415ccfa365d (patch)
treea72a209c803887d244c57b5c72d20a4d33b3419d /mm/page_alloc.c
parent70427f6e9ecfc8c5f977b21dd9f846b3bda02500 (diff)
downloadlinux-dac22531bbd4af2426c4e29e05594415ccfa365d.tar.xz
mm: prevent page_frag_alloc() from corrupting the memory
A number of drivers call page_frag_alloc() with a fragment's size > PAGE_SIZE. In low memory conditions, __page_frag_cache_refill() may fail the order 3 cache allocation and fall back to order 0; In this case, the cache will be smaller than the fragment, causing memory corruptions. Prevent this from happening by checking if the newly allocated cache is large enough for the fragment; if not, the allocation will fail and page_frag_alloc() will return NULL. Link: https://lkml.kernel.org/r/20220715125013.247085-1-mlombard@redhat.com Fixes: b63ae8ca096d ("mm/net: Rename and move page fragment handling from net/ to mm/") Signed-off-by: Maurizio Lombardi <mlombard@redhat.com> Reviewed-by: Alexander Duyck <alexanderduyck@fb.com> Cc: Chen Lin <chen45464546@163.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1678431fb4c4..d04211f0ef0b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5740,6 +5740,18 @@ refill:
/* reset page count bias and offset to start of new frag */
nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1;
offset = size - fragsz;
+ if (unlikely(offset < 0)) {
+ /*
+ * The caller is trying to allocate a fragment
+ * with fragsz > PAGE_SIZE but the cache isn't big
+ * enough to satisfy the request, this may
+ * happen in low memory conditions.
+ * We don't release the cache page because
+ * it could make memory pressure worse
+ * so we simply return NULL here.
+ */
+ return NULL;
+ }
}
nc->pagecnt_bias--;