For debugging, object_err() prints free pointer of the object. However, if object is a invalid pointer, dereferncing `object + s->offset` can lead to a crash. Therefore, add check_valid_pointer() for the object.

Fixes: 81819f0fc828 ("SLUB core") Cc: stable@vger.kernel.org Signed-off-by: Li Qiong liqiong@nfschina.com --- v2: - rephrase the commit message, add comment for object_err(). v3: - check object pointer in object_err(). v4: - restore changes in alloc_consistency_checks(). --- mm/slub.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mm/slub.c b/mm/slub.c index 31e11ef256f9..17b91e74f7d9 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1104,7 +1104,11 @@ static void object_err(struct kmem_cache *s, struct slab *slab, return;

slab_bug(s, reason); - print_trailer(s, slab, object); + if (!check_valid_pointer(s, slab, object)) { + print_slab_info(slab); + pr_err("invalid object 0x%p\n", object); + } else + print_trailer(s, slab, object); add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);

WARN_ON(1);