From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 349A627707 for ; Sun, 7 Sep 2025 02:27:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757212056; cv=none; b=us11Ml8l1wRI6Y0EGpGMV42dtl89/4CpgsflDbGBw1X7X1h+3zOmOVBa72rubTremkLFWieMdAzoOmMOFb9VkG8xFbnPPxfpnqCZJ7aMynOAc84x0DTPKCP7ioPKlaqtI1T616s3kOXCErOr4b7sbAlK3Y44BON8DmPu/JKR0rw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757212056; c=relaxed/simple; bh=0rB1T3W8IbmzS2nz38OFj8dj/ItPzLmz4eJ/5it+KcQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LWLnKXIxX4bGUQG47q/ocIRci4S5oUqyD+uvF7kqrmnLQq0+DKYGZjoqOyW52qBxK6GA9BK0GVaao4l8ImTMoq5r0OyaRFAhSughLx0FA3XNpYzzN5OZJ7FHoMc8O8mevZn1alRXnDG2Yf1VPnkAs+2LG7jXmAnrlI5nApcyzek= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=vDugXCVI; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="vDugXCVI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 160D9C4CEE7; Sun, 7 Sep 2025 02:27:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1757212055; bh=0rB1T3W8IbmzS2nz38OFj8dj/ItPzLmz4eJ/5it+KcQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vDugXCVI1koh/aLVVASqLCMXMGJfBY26mjhSTYNHSYT1kw9IWvK4JLEjWdhSEFaWR K+aSW69UznIKQwsNFKuIuV9lJq4W4+zCxV5b9V95oGFSjWJQrPz0zr7CNfjwRPBYU4 XOITMlvEmuE0wjO928LFSX2kK1rvXlz0SZUnazQdBFDnA9VXIab0PBIbPwuEUlLz7Y ZdmxPWlCcox8SbTbONxjmSDw2ANDdPCQ3lbdLx+CwDP9IfeE5f19kbvcEl2jk/mkdp 9d6ShqeuqwtV0FYUQKERcMvPPQLfYogob1WT7nZ06pk7yQoG7Z+l/Vhdn1XqmKXmzb wMKhAkO7I0rEg== From: Sasha Levin To: stable@vger.kernel.org Cc: Li Qiong , Harry Yoo , "Matthew Wilcox (Oracle)" , Vlastimil Babka , Sasha Levin Subject: [PATCH 5.10.y] mm/slub: avoid accessing metadata when pointer is invalid in object_err() Date: Sat, 6 Sep 2025 22:27:33 -0400 Message-ID: <20250907022733.411422-1-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <2025090621-plank-carry-3541@gregkh> References: <2025090621-plank-carry-3541@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Li Qiong [ 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: Signed-off-by: Li Qiong Reviewed-by: Harry Yoo Reviewed-by: Matthew Wilcox (Oracle) Signed-off-by: Vlastimil Babka [ struct page + print_page_info() ] Signed-off-by: Sasha Levin --- mm/slub.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index b0f637519ac99..30daba09da35d 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -729,7 +729,12 @@ 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, -- 2.51.0