From nobody Thu Feb 12 07:39:14 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 2D955C7618E for ; Wed, 26 Apr 2023 17:18:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233390AbjDZRSP (ORCPT ); Wed, 26 Apr 2023 13:18:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40586 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234727AbjDZRRx (ORCPT ); Wed, 26 Apr 2023 13:17:53 -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 7034F6A54 for ; Wed, 26 Apr 2023 10:17:52 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A31286370D for ; Wed, 26 Apr 2023 17:17:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 17ED6C433A4; Wed, 26 Apr 2023 17:17:51 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.96) (envelope-from ) id 1prim6-005KZr-0g; Wed, 26 Apr 2023 13:17:50 -0400 Message-ID: <20230426171750.028699848@goodmis.org> User-Agent: quilt/0.66 Date: Wed, 26 Apr 2023 13:17:08 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Andrew Morton , Doug Cook , Beau Belgrave Subject: [for-next][PATCH 05/11] tracing/user_events: Ensure write index cannot be negative References: <20230426171703.202523909@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: Beau Belgrave The write index indicates which event the data is for and accesses a per-file array. The index is passed by user processes during write() calls as the first 4 bytes. Ensure that it cannot be negative by returning -EINVAL to prevent out of bounds accesses. Update ftrace self-test to ensure this occurs properly. Link: https://lkml.kernel.org/r/20230425225107.8525-2-beaub@linux.microsoft= .com Fixes: 7f5a08c79df3 ("user_events: Add minimal support for trace_event into= ftrace") Reported-by: Doug Cook Signed-off-by: Beau Belgrave Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_user.c | 3 +++ tools/testing/selftests/user_events/ftrace_test.c | 5 +++++ 2 files changed, 8 insertions(+) diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_u= ser.c index eadb58a3efba..546d47a57520 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -1824,6 +1824,9 @@ static ssize_t user_events_write_core(struct file *fi= le, struct iov_iter *i) if (unlikely(copy_from_iter(&idx, sizeof(idx), i) !=3D sizeof(idx))) return -EFAULT; =20 + if (idx < 0) + return -EINVAL; + rcu_read_lock_sched(); =20 refs =3D rcu_dereference_sched(info->refs); diff --git a/tools/testing/selftests/user_events/ftrace_test.c b/tools/test= ing/selftests/user_events/ftrace_test.c index aceafacfb126..91272f9d6fce 100644 --- a/tools/testing/selftests/user_events/ftrace_test.c +++ b/tools/testing/selftests/user_events/ftrace_test.c @@ -296,6 +296,11 @@ TEST_F(user, write_events) { ASSERT_NE(-1, writev(self->data_fd, (const struct iovec *)io, 3)); after =3D trace_bytes(); ASSERT_GT(after, before); + + /* Negative index should fail with EINVAL */ + reg.write_index =3D -1; + ASSERT_EQ(-1, writev(self->data_fd, (const struct iovec *)io, 3)); + ASSERT_EQ(EINVAL, errno); } =20 TEST_F(user, write_fault) { --=20 2.39.2