From: Li Qiong Date: Mon, 4 Aug 2025 02:57:59 +0000 (+0800) Subject: mm/slub: avoid accessing metadata when pointer is invalid in object_err() X-Git-Tag: v6.17-rc5~22^2~1 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=b4efccec8d06ceb10a7d34d7b1c449c569d53770;p=linux-block.git mm/slub: avoid accessing metadata when pointer is invalid in object_err() object_err() reports details of an object for further debugging, such as the freelist pointer, redzone, etc. However, if the pointer is invalid, attempting to access object metadata can lead to a crash since it does not point to a valid object. One known path to the crash is when alloc_consistency_checks() determines the pointer to the allocated object is invalid because of a freelist corruption, and calls object_err() to report it. The debug code should report and handle the corruption gracefully and not crash in the process. In case the pointer is NULL or check_valid_pointer() returns false for the pointer, only print the pointer value and skip accessing metadata. Fixes: 81819f0fc828 ("SLUB core") Cc: Signed-off-by: Li Qiong Reviewed-by: Harry Yoo Reviewed-by: Matthew Wilcox (Oracle) Signed-off-by: Vlastimil Babka --- diff --git a/mm/slub.c b/mm/slub.c index 30003763d224..1787e4d51e48 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1140,7 +1140,12 @@ static void object_err(struct kmem_cache *s, struct slab *slab, return; slab_bug(s, reason); - print_trailer(s, slab, object); + if (!object || !check_valid_pointer(s, slab, object)) { + print_slab_info(slab); + pr_err("Invalid pointer 0x%p\n", object); + } else { + print_trailer(s, slab, object); + } add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); WARN_ON(1);