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authorAndrey Konovalov <andreyknvl@google.com>2022-01-14 14:05:01 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2022-01-15 16:30:26 +0200
commit26dca996ea7b1ac7008b6b6063fc88b849e3ac3e (patch)
treecba343dcba067570b75226033f93f85de5310c17 /mm/kasan
parentf98f966cd75002a71caec1b6d209da5762c0efac (diff)
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: 6471384af2a6 ("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>
Diffstat (limited to 'mm/kasan')
-rw-r--r--mm/kasan/quarantine.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
index d8ccff4c1275..47ed4fc33a29 100644
--- a/mm/kasan/quarantine.c
+++ b/mm/kasan/quarantine.c
@@ -132,12 +132,23 @@ 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* free track is no longer valid.
*/