From nobody Sun Feb 8 10:34:15 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12ACFEB64DA for ; Wed, 5 Jul 2023 14:46:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232642AbjGEOqi (ORCPT ); Wed, 5 Jul 2023 10:46:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52810 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232113AbjGEOqf (ORCPT ); Wed, 5 Jul 2023 10:46:35 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3D96F1B6; Wed, 5 Jul 2023 07:46:34 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 98FB8612B1; Wed, 5 Jul 2023 14:46:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0DA7BC433C9; Wed, 5 Jul 2023 14:46:32 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.96) (envelope-from ) id 1qH3m4-003Pgs-0D; Wed, 05 Jul 2023 10:46:32 -0400 Message-ID: <20230705144631.880308757@goodmis.org> User-Agent: quilt/0.66 Date: Wed, 05 Jul 2023 10:40:32 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Andrew Morton , stable@vger.kernel.org, Mateusz Stachyra Subject: [for-linus][PATCH 1/3] tracing: Fix null pointer dereference in tracing_err_log_open() References: <20230705144031.702796304@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Mateusz Stachyra Fix an issue in function 'tracing_err_log_open'. The function doesn't call 'seq_open' if the file is opened only with write permissions, which results in 'file->private_data' being left as null. If we then use 'lseek' on that opened file, 'seq_lseek' dereferences 'file->private_data' in 'mutex_lock(&m->lock)', resulting in a kernel panic. Writing to this node requires root privileges, therefore this bug has very little security impact. Tracefs node: /sys/kernel/tracing/error_log Example Kernel panic: Unable to handle kernel NULL pointer dereference at virtual address 0000000= 000000038 Call trace: mutex_lock+0x30/0x110 seq_lseek+0x34/0xb8 __arm64_sys_lseek+0x6c/0xb8 invoke_syscall+0x58/0x13c el0_svc_common+0xc4/0x10c do_el0_svc+0x24/0x98 el0_svc+0x24/0x88 el0t_64_sync_handler+0x84/0xe4 el0t_64_sync+0x1b4/0x1b8 Code: d503201f aa0803e0 aa1f03e1 aa0103e9 (c8e97d02) Acked-by: Masami Hiramatsu (Google) Suggested-by: Steven Rostedt ---[ end trace 561d1b49c12cf8a5 ]--- Kernel panic - not syncing: Oops: Fatal exception Link: https://lore.kernel.org/linux-trace-kernel/20230703155237eucms1p4dfb6= a19caa14c79eb6c823d127b39024@eucms1p4 Link: https://lore.kernel.org/linux-trace-kernel/20230704102706eucms1p30d7e= cdcc287f46ad67679fc8491b2e0f@eucms1p3 Cc: stable@vger.kernel.org Fixes: 8a062902be725 ("tracing: Add tracing error log") Signed-off-by: Mateusz Stachyra Suggested-by: Steven Rostedt Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 64a4dde073ef..3d34e6fea6b2 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -8135,7 +8135,7 @@ static const struct file_operations tracing_err_log_f= ops =3D { .open =3D tracing_err_log_open, .write =3D tracing_err_log_write, .read =3D seq_read, - .llseek =3D seq_lseek, + .llseek =3D tracing_lseek, .release =3D tracing_err_log_release, }; =20 --=20 2.39.2