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kasan: fix quarantine conflicting with init_on_free 

KASAN's quarantine might save its metadata inside freed objects.  As
this happens after the memory is zeroed by the slab allocator when
init_on_free is enabled, the memory coming out of quarantine is not
properly zeroed.

This causes lib/test_meminit.c tests to fail with Generic KASAN.

Zero the metadata when the object is removed from quarantine.

Link: https://lkml.kernel.org/r/2805da5df4b57138fdacd671f5d227d58950ba54.1640037083.git.andreyknvl@google.com
Fixes: 6471384af2 ("mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options")
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrey Konovalov 2022-01-14 14:05:01 -08:00 committed by Linus Torvalds
parent f98f966cd7
commit 26dca996ea
1 changed files with 11 additions and 0 deletions
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11
mm/kasan/quarantine.c
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@ -132,11 +132,22 @@ static void *qlink_to_object(struct qlist_node *qlink, struct kmem_cache *cache)
static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
{
void *object = qlink_to_object(qlink, cache);
struct kasan_free_meta *meta = kasan_get_free_meta(cache, object);
unsigned long flags;
if (IS_ENABLED(CONFIG_SLAB))
local_irq_save(flags);
/*
* If init_on_free is enabled and KASAN's free metadata is stored in
* the object, zero the metadata. Otherwise, the object's memory will
* not be properly zeroed, as KASAN saves the metadata after the slab
* allocator zeroes the object.
*/
if (slab_want_init_on_free(cache) &&
cache->kasan_info.free_meta_offset == 0)
memzero_explicit(meta, sizeof(*meta));
/*
* As the object now gets freed from the quarantine, assume that its
* free track is no longer valid.