path: root/include
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authorKees Cook <>2021-06-15 18:23:26 -0700
committerLinus Torvalds <>2021-06-16 09:24:42 -0700
commite41a49fadbc80b60b48d3c095d9e2ee7ef7c9a8e (patch)
tree8e419e9ec3faa2d56987d65e4b3a1e1e82dbe08b /include
parent74c1d3e081533825f2611e46edea1fcdc0701985 (diff)
mm/slub: actually fix freelist pointer vs redzoning
It turns out that SLUB redzoning ("slub_debug=Z") checks from s->object_size rather than from s->inuse (which is normally bumped to make room for the freelist pointer), so a cache created with an object size less than 24 would have the freelist pointer written beyond s->object_size, causing the redzone to be corrupted by the freelist pointer. This was very visible with "slub_debug=ZF": BUG test (Tainted: G B ): Right Redzone overwritten ----------------------------------------------------------------------------- INFO: 0xffff957ead1c05de-0xffff957ead1c05df @offset=1502. First byte 0x1a instead of 0xbb INFO: Slab 0xffffef3950b47000 objects=170 used=170 fp=0x0000000000000000 flags=0x8000000000000200 INFO: Object 0xffff957ead1c05d8 @offset=1496 fp=0xffff957ead1c0620 Redzone (____ptrval____): bb bb bb bb bb bb bb bb ........ Object (____ptrval____): 00 00 00 00 00 f6 f4 a5 ........ Redzone (____ptrval____): 40 1d e8 1a aa @.... Padding (____ptrval____): 00 00 00 00 00 00 00 00 ........ Adjust the offset to stay within s->object_size. (Note that no caches of in this size range are known to exist in the kernel currently.) Link: Link: Link: 89b83f282d8b (slub: avoid redzone when choosing freepointer location) Link: Signed-off-by: Kees Cook <> Reported-by: Marco Elver <> Reported-by: "Lin, Zhenpeng" <> Tested-by: Marco Elver <> Acked-by: Vlastimil Babka <> Cc: Christoph Lameter <> Cc: David Rientjes <> Cc: Joonsoo Kim <> Cc: Pekka Enberg <> Cc: Roman Gushchin <> Cc: <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'include')
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