From: Li Qiong liqiong@nfschina.com
[ 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 --- mm/slub.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/mm/slub.c b/mm/slub.c index e978f647e92aa..734f763e7d2e2 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -719,7 +719,12 @@ 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,