The patch titled
Subject: kasan, slub: fix more conflicts with CONFIG_SLAB_FREELIST_HARDENED
has been added to the -mm tree. Its filename is
kasan-slub-fix-more-conflicts-with-config_slab_freelist_hardened.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kasan-slub-fix-more-conflicts-with-config_slab_freelist_hardened.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kasan-slub-fix-more-conflicts-with-config_slab_freelist_hardened.patch
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------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: kasan, slub: fix more conflicts with CONFIG_SLAB_FREELIST_HARDENED
When CONFIG_KASAN_SW_TAGS is enabled, ptr_addr might be tagged. Normally,
this doesn't cause any issues, as both set_freepointer() and
get_freepointer() are called with a pointer with the same tag. However,
there are some issues with CONFIG_SLUB_DEBUG code. For example, when
__free_slub() iterates over objects in a cache, it passes untagged
pointers to check_object(). check_object() in turns calls
get_freepointer() with an untagged pointer, which causes the freepointer
to be restored incorrectly.
Add kasan_reset_tag to freelist_ptr(). Also add a detailed comment.
Link: http://lkml.kernel.org/r/bf858f26ef32eb7bd24c665755b3aee4bc58d0e4.1550103861.git.andreyknvl@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reported-by: Qian Cai <cai@xxxxxx>
Tested-by: Qian Cai <cai@xxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slub.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
--- a/mm/slub.c~kasan-slub-fix-more-conflicts-with-config_slab_freelist_hardened
+++ a/mm/slub.c
@@ -249,7 +249,18 @@ static inline void *freelist_ptr(const s
unsigned long ptr_addr)
{
#ifdef CONFIG_SLAB_FREELIST_HARDENED
- return (void *)((unsigned long)ptr ^ s->random ^ ptr_addr);
+ /*
+ * When CONFIG_KASAN_SW_TAGS is enabled, ptr_addr might be tagged.
+ * Normally, this doesn't cause any issues, as both set_freepointer()
+ * and get_freepointer() are called with a pointer with the same tag.
+ * However, there are some issues with CONFIG_SLUB_DEBUG code. For
+ * example, when __free_slub() iterates over objects in a cache, it
+ * passes untagged pointers to check_object(). check_object() in turns
+ * calls get_freepointer() with an untagged pointer, which causes the
+ * freepointer to be restored incorrectly.
+ */
+ return (void *)((unsigned long)ptr ^ s->random ^
+ (unsigned long)kasan_reset_tag((void *)ptr_addr));
#else
return ptr;
#endif
_
Patches currently in -mm which might be from andreyknvl@xxxxxxxxxx are
kasan-fix-assigning-tags-twice.patch
kasan-kmemleak-pass-tagged-pointers-to-kmemleak.patch
kmemleak-account-for-tagged-pointers-when-calculating-pointer-range-v2.patch
kasan-slub-move-kasan_poison_slab-hook-before-page_address.patch
kasan-slub-move-kasan_poison_slab-hook-before-page_address-v2.patch
kasan-slub-fix-conflicts-with-config_slab_freelist_hardened.patch
kasan-slub-fix-more-conflicts-with-config_slab_freelist_hardened.patch
