From: Alexander Popov <alex.popov@xxxxxxxxx> Subject: mm/slub.c: add a naive detection of double free or corruption Add an assertion similar to "fasttop" check in GNU C Library allocator as a part of SLAB_FREELIST_HARDENED feature. An object added to a singly linked freelist should not point to itself. That helps to detect some double free errors (e.g. CVE-2017-2636) without slub_debug and KASAN. Link: http://lkml.kernel.org/r/1502468246-1262-1-git-send-email-alex.popov@xxxxxxxxx Signed-off-by: Alexander Popov <alex.popov@xxxxxxxxx> Acked-by: Christoph Lameter <cl@xxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Paul E McKenney <paulmck@xxxxxxxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Nicolas Pitre <nicolas.pitre@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Tycho Andersen <tycho@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/slub.c | 4 ++++ 1 file changed, 4 insertions(+) diff -puN mm/slub.c~mm-slubc-add-a-naive-detection-of-double-free-or-corruption mm/slub.c --- a/mm/slub.c~mm-slubc-add-a-naive-detection-of-double-free-or-corruption +++ a/mm/slub.c @@ -290,6 +290,10 @@ static inline void set_freepointer(struc { unsigned long freeptr_addr = (unsigned long)object + s->offset; +#ifdef CONFIG_SLAB_FREELIST_HARDENED + BUG_ON(object == fp); /* naive detection of double free or corruption */ +#endif + *(void **)freeptr_addr = freelist_ptr(s, fp, freeptr_addr); } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
