For debugging, object_err() prints free pointer of the object. However, if check_valid_pointer() returns false for a object, dereferncing `object + s->offset` can lead to a crash. Therefore, print the object's address in such cases.
Fixes: bb192ed9aa71 ("mm/slub: Convert most struct page to struct slab by spatch") 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(). --- mm/slub.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c index 31e11ef256f9..d3abae5a2193 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); @@ -1587,7 +1591,7 @@ static inline int alloc_consistency_checks(struct kmem_cache *s, return 0;
if (!check_valid_pointer(s, slab, object)) { - object_err(s, slab, object, "Freelist Pointer check fails"); + slab_err(s, slab, "Freelist Pointer(0x%p) check fails", object); return 0; }