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author | Maurizio Lombardi <mlombard@redhat.com> | 2022-07-15 15:50:13 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-10-05 11:36:44 +0300 |
commit | 39a22a4ccd3a6c073ba2257629e752afa4e7ad08 (patch) | |
tree | 38724d41fc69cc5a41c6aca55091d96d97699cd3 /mm | |
parent | 26e871af465dff04431b03ba9c71144f63e59599 (diff) | |
download | linux-39a22a4ccd3a6c073ba2257629e752afa4e7ad08.tar.xz |
mm: prevent page_frag_alloc() from corrupting the memory
commit dac22531bbd4af2426c4e29e05594415ccfa365d upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/page_alloc.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 134bdf345389..1cffd4e1fd8f 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4603,6 +4603,18 @@ 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--; |