* [to-be-updated] mm-kcsan-instrument-slab-slub-free-with-assert_exclusive_access.patch removed from -mm tree
@ 2020-06-24 21:59 akpm
0 siblings, 0 replies; only message in thread
From: akpm @ 2020-06-24 21:59 UTC (permalink / raw)
To: mm-commits, rientjes, penberg, iamjoonsoo.kim, glider, cl,
andreyknvl, elver
The patch titled
Subject: mm, kcsan: instrument SLAB/SLUB free with "ASSERT_EXCLUSIVE_ACCESS"
has been removed from the -mm tree. Its filename was
mm-kcsan-instrument-slab-slub-free-with-assert_exclusive_access.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------
From: Marco Elver <elver@google.com>
Subject: mm, kcsan: instrument SLAB/SLUB free with "ASSERT_EXCLUSIVE_ACCESS"
Provide the necessary KCSAN checks to assist with debugging racy
use-after-frees. While KASAN is more reliable at generally catching such
use-after-frees (due to its use of a quarantine), it can be difficult to
debug racy use-after-frees. If a reliable reproducer exists, KCSAN can
assist in debugging such issues.
Note: ASSERT_EXCLUSIVE_ACCESS is a convenience wrapper if the size is
simply sizeof(var). Instead, here we just use __kcsan_check_access()
explicitly to pass the correct size.
Link: http://lkml.kernel.org/r/20200616125617.237428-1-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/slab.c | 4 ++++
mm/slub.c | 4 ++++
2 files changed, 8 insertions(+)
--- a/mm/slab.c~mm-kcsan-instrument-slab-slub-free-with-assert_exclusive_access
+++ a/mm/slab.c
@@ -3426,6 +3426,10 @@ static __always_inline void __cache_free
if (kasan_slab_free(cachep, objp, _RET_IP_))
return;
+ /* Use KCSAN to help debug racy use-after-free. */
+ __kcsan_check_access(objp, cachep->object_size,
+ KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ASSERT);
+
___cache_free(cachep, objp, caller);
}
--- a/mm/slub.c~mm-kcsan-instrument-slab-slub-free-with-assert_exclusive_access
+++ a/mm/slub.c
@@ -1549,6 +1549,10 @@ static __always_inline bool slab_free_ho
if (!(s->flags & SLAB_DEBUG_OBJECTS))
debug_check_no_obj_freed(x, s->object_size);
+ /* Use KCSAN to help debug racy use-after-free. */
+ __kcsan_check_access(x, s->object_size,
+ KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ASSERT);
+
/* KASAN might put x into memory quarantine, delaying its reuse */
return kasan_slab_free(s, x, _RET_IP_);
}
_
Patches currently in -mm which might be from elver@google.com are
kcov-unconditionally-add-fno-stack-protector-to-compiler-options.patch
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2020-06-24 21:59 [to-be-updated] mm-kcsan-instrument-slab-slub-free-with-assert_exclusive_access.patch removed from -mm tree akpm
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