From: Li Qiong <liqiong@nfschina.com> stable inclusion from stable-v5.4.299 commit 872f2c34ff232af1e65ad2df86d61163c8ffad42 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ID0R2Y CVE: CVE-2025-39902 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit b4efccec8d06ceb10a7d34d7b1c449c569d53770 ] 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: <stable@vger.kernel.org> Signed-off-by: Li Qiong <liqiong@nfschina.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> [ struct page + print_page_info() ] Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com> --- mm/slub.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index a67bcc57a770..4afdf67e4c58 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -711,11 +711,16 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p) void object_err(struct kmem_cache *s, struct page *page, u8 *object, char *reason) { slab_bug(s, "%s", reason); - print_trailer(s, page, object); + if (!object || !check_valid_pointer(s, page, object)) { + print_page_info(page); + pr_err("Invalid pointer 0x%p\n", object); + } else { + print_trailer(s, page, object); + } } static __printf(3, 4) void slab_err(struct kmem_cache *s, struct page *page, const char *fmt, ...) { -- 2.43.0