summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorAndrey Konovalov <andreyknvl@gmail.com>2024-01-09 23:12:34 +0100
committerAndrew Morton <akpm@linux-foundation.org>2024-01-12 15:20:45 -0800
commitcc478e0b6bdffd20561e1a07941a65f6c8962cab (patch)
tree36e164b0477fa685f44d53fdc8deaac90225227a
parentaaa2c9a97c22af5bf011f6dd8e0538219b45af88 (diff)
kasan: avoid resetting aux_lock
With commit 63b85ac56a64 ("kasan: stop leaking stack trace handles"), KASAN zeroes out alloc meta when an object is freed. The zeroed out data purposefully includes alloc and auxiliary stack traces but also accidentally includes aux_lock. As aux_lock is only initialized for each object slot during slab creation, when the freed slot is reallocated, saving auxiliary stack traces for the new object leads to lockdep reports when taking the zeroed out aux_lock. Arguably, we could reinitialize aux_lock when the object is reallocated, but a simpler solution is to avoid zeroing out aux_lock when an object gets freed. Link: https://lkml.kernel.org/r/20240109221234.90929-1-andrey.konovalov@linux.dev Fixes: 63b85ac56a64 ("kasan: stop leaking stack trace handles") Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com> Reported-by: Paul E. McKenney <paulmck@kernel.org> Closes: https://lore.kernel.org/linux-next/5cc0f83c-e1d6-45c5-be89-9b86746fe731@paulmck-laptop/ Reviewed-by: Marco Elver <elver@google.com> Tested-by: Paul E. McKenney <paulmck@kernel.org> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Liam R. Howlett <Liam.Howlett@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--mm/kasan/generic.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 24c13dfb1e94..df6627f62402 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -487,6 +487,7 @@ void kasan_init_object_meta(struct kmem_cache *cache, const void *object)
__memset(alloc_meta, 0, sizeof(*alloc_meta));
/*
+ * Prepare the lock for saving auxiliary stack traces.
* Temporarily disable KASAN bug reporting to allow instrumented
* raw_spin_lock_init to access aux_lock, which resides inside
* of a redzone.
@@ -510,8 +511,13 @@ static void release_alloc_meta(struct kasan_alloc_meta *meta)
stack_depot_put(meta->aux_stack[0]);
stack_depot_put(meta->aux_stack[1]);
- /* Zero out alloc meta to mark it as invalid. */
- __memset(meta, 0, sizeof(*meta));
+ /*
+ * Zero out alloc meta to mark it as invalid but keep aux_lock
+ * initialized to avoid having to reinitialize it when another object
+ * is allocated in the same slot.
+ */
+ __memset(&meta->alloc_track, 0, sizeof(meta->alloc_track));
+ __memset(meta->aux_stack, 0, sizeof(meta->aux_stack));
}
static void release_free_meta(const void *object, struct kasan_free_meta *meta)