diff options
| author | Benjamin Gray <bgray@linux.ibm.com> | 2024-02-13 14:39:58 +1100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-02-20 14:20:50 -0800 |
| commit | 2597c9947b0174fcc71bdd7ab6cb49c2b4291e95 (patch) | |
| tree | 67ea3b20b254357b0e4a17e403181dcce2309f0c /mm/kasan | |
| parent | 13d0599ab3b2ff17f798353f24bcbef1659d3cfc (diff) | |
kasan: guard release_free_meta() shadow access with kasan_arch_is_ready()
release_free_meta() accesses the shadow directly through the path
kasan_slab_free
__kasan_slab_free
kasan_release_object_meta
release_free_meta
kasan_mem_to_shadow
There are no kasan_arch_is_ready() guards here, allowing an oops when the
shadow is not initialized. The oops can be seen on a Power8 KVM guest.
This patch adds the guard to release_free_meta(), as it's the first level
that specifically requires the shadow.
It is safe to put the guard at the start of this function, before the
stack put: only kasan_save_free_info() can initialize the saved stack,
which itself is guarded with kasan_arch_is_ready() by its caller
poison_slab_object(). If the arch becomes ready before
release_free_meta() then we will not observe KASAN_SLAB_FREE_META in the
object's shadow, so we will not put an uninitialized stack either.
Link: https://lkml.kernel.org/r/20240213033958.139383-1-bgray@linux.ibm.com
Fixes: 63b85ac56a64 ("kasan: stop leaking stack trace handles")
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/kasan')
| -rw-r--r-- | mm/kasan/generic.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c index df6627f62402..032bf3e98c24 100644 --- a/mm/kasan/generic.c +++ b/mm/kasan/generic.c @@ -522,6 +522,9 @@ static void release_alloc_meta(struct kasan_alloc_meta *meta) static void release_free_meta(const void *object, struct kasan_free_meta *meta) { + if (!kasan_arch_is_ready()) + return; + /* Check if free meta is valid. */ if (*(u8 *)kasan_mem_to_shadow(object) != KASAN_SLAB_FREE_META) return; |