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 E8BC75223 for ; Sun, 7 Sep 2025 01:26:44 +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=1757208405; cv=none; b=ABnfqTTXhZKHBB8VxMx5vMzD8DBLethnbc2h5K7zSaTrJmfPTRztvCFUZEwO50Rif2iowTJrpALeA/CkP8SVCOxgJOHd0rAZgijohF71Nv7/XoI/60lVKnmnVZ/hcLYEyrXBv1H6GzQTSOum/WiPv1yXa9DLg2OyNE7l/fiPh3Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757208405; c=relaxed/simple; bh=toH7jb/Tqc9r2lRQ4ZSLEpFNP0YKoZexKBMR/21N5Qw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AyfQENNgXQMFJFeDjfwju5D/d/j1MI2HbweZsRUISdh1pm4PR3BiZ82zD44/7eLWSYJTzkqoq1A3BRLGtaDT0Wa3uQH3pzXTumJtPAByWWEZ+gXJuqGRrzZF/KLX4k9deA+xs5CTH6apye+9ZjcTlRV0GWLfAN6j+tXxILRFHo8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=H/n6xcy0; 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="H/n6xcy0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B4761C4CEE7; Sun, 7 Sep 2025 01:26:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1757208404; bh=toH7jb/Tqc9r2lRQ4ZSLEpFNP0YKoZexKBMR/21N5Qw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H/n6xcy0HmyynRru0PEhTHJ6gCmu84DKXyP3GRyXjQYvZetUveZ6LoYoAG0UP3t18 UFdStka/Il/vD657M1dRfSX1sII030XQCpw5KudFC3vcaI5mQEWGNTPHyARVGzL5LG k/Ldecxk7mXVT+DvQ6a/FpffNdvbGuiXm2xWh6m/n8cEY1fOiLeV/qyD6xdeXRGo/O ZeGia9skUf+K5rK3QsgaDT8OG/9AD8bioulcbml9v/ZBlkz0l7FOsIvLsh/9Rs1b5j XLtFZWbW3WrqKwgdSgsj2TEWd4TMHTYRwbzij7EluxemDYLxCIdG8A7y8qsx7YbEK1 NtK1qpuMtN1vg== From: Sasha Levin To: stable@vger.kernel.org Cc: Li Qiong , Harry Yoo , "Matthew Wilcox (Oracle)" , Vlastimil Babka , Sasha Levin Subject: [PATCH 6.1.y] mm/slub: avoid accessing metadata when pointer is invalid in object_err() Date: Sat, 6 Sep 2025 21:26:41 -0400 Message-ID: <20250907012641.385388-1-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <2025090620-evaluator-visiting-ac7e@gregkh> References: <2025090620-evaluator-visiting-ac7e@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 [ Adjust context ] 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 157527d7101be..f118fcc6af6e4 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -927,7 +927,12 @@ static void object_err(struct kmem_cache *s, struct slab *slab, return; slab_bug(s, "%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); } -- 2.51.0