* [kernel-hardening] [linux-next][PATCH v2] mm/slub.c: add a naive detection of double free or corruption
@ 2017-08-11 16:17 Alexander Popov
2017-08-11 17:26 ` [kernel-hardening] " Christopher Lameter
0 siblings, 1 reply; 2+ messages in thread
From: Alexander Popov @ 2017-08-11 16:17 UTC (permalink / raw)
To: Kees Cook, Andrew Morton, Christoph Lameter, Pekka Enberg,
David Rientjes, Joonsoo Kim, Paul E McKenney, Ingo Molnar,
Tejun Heo, Andy Lutomirski, Nicolas Pitre, linux-mm,
Rik van Riel, Tycho Andersen, Alexander Popov, linux-kernel,
kernel-hardening
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.
Signed-off-by: Alexander Popov <alex.popov@linux.com>
---
mm/slub.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/mm/slub.c b/mm/slub.c
index b9c7f1a..77b2781 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -290,6 +290,10 @@ static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp)
{
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);
}
--
2.7.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [kernel-hardening] Re: [linux-next][PATCH v2] mm/slub.c: add a naive detection of double free or corruption
2017-08-11 16:17 [kernel-hardening] [linux-next][PATCH v2] mm/slub.c: add a naive detection of double free or corruption Alexander Popov
@ 2017-08-11 17:26 ` Christopher Lameter
0 siblings, 0 replies; 2+ messages in thread
From: Christopher Lameter @ 2017-08-11 17:26 UTC (permalink / raw)
To: Alexander Popov
Cc: Kees Cook, Andrew Morton, Pekka Enberg, David Rientjes,
Joonsoo Kim, Paul E McKenney, Ingo Molnar, Tejun Heo,
Andy Lutomirski, Nicolas Pitre, linux-mm, Rik van Riel,
Tycho Andersen, linux-kernel, kernel-hardening
On Fri, 11 Aug 2017, Alexander Popov wrote:
> 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.
Acked-by: Christoph Lameter <cl@linux.com>
^ permalink raw reply [flat|nested] 2+ messages in thread
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