[PATCH 5.15 093/262] kasan: fix quarantine conflicting with init_on_free
From: Greg Kroah-Hartman
Date: Mon Mar 07 2022 - 05:05:07 EST
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
[ Upstream commit 26dca996ea7b1ac7008b6b6063fc88b849e3ac3e ]
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@xxxxxxxxxx
Fixes: 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options")
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
mm/kasan/quarantine.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
index d8ccff4c1275e..47ed4fc33a29e 100644
--- a/mm/kasan/quarantine.c
+++ b/mm/kasan/quarantine.c
@@ -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* free track is no longer valid.
--
2.34.1