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: b63ae8ca ("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>
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