From nobody Sat Oct 4 04:56:43 2025 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 D2746DF76; Thu, 21 Aug 2025 00:00:11 +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=1755734411; cv=none; b=ZT9ZnGLCcsqUJZpohhEtW2I19Zi1fY1yDJ7A9ujrRjEMR9pbuE0q2S71HiEBOvGusZ/jks64OfvcCD565DICnNwRXG1c0n7ISNyDQ/L67ghnDBzX8GnMtjbQS2ToLnr8+eis8MpqGfuqmaJ0G71XQ6Huf6GYzemaA/0AJjIyTdo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755734411; c=relaxed/simple; bh=qM0M8s3MHhu7f4tMuCurJwd+EN9+GJIDPE7Cse4PGIs=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=lOoJ5qAS5c2JJChvZAs7sfp0nW8pNylBaQ0kApndqFFDmDJyjvlj4JfRsUKfVeuw+xMgGlD4XlO3bPjPe1QmXHPLzmbND4z/kXGrknighwe2P53qXi0Xfj3novacYx5Fa9eTPhf3M2E0tQ/8ooF5VQqOV2nO6OHUe8NaH/wzvpg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LanWacx1; 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="LanWacx1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5AD50C16AAE; Thu, 21 Aug 2025 00:00:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755734411; bh=qM0M8s3MHhu7f4tMuCurJwd+EN9+GJIDPE7Cse4PGIs=; h=Date:From:To:Cc:Subject:References:From; b=LanWacx1J2ziGQIyrOfW5W60VavFaSVuuWs4YjTMStEFpI82FMeDx4pBhaNY2ugYO h/oZ7jWJfeL0fkKzTLN20X/AGXckiJMPrqrbxm7/xUTrmksJp6tx1PuhiAoeDXYMV4 0N7fTqwN3HYdFwBHnjrIUtM7thQ8JGahiR9weBKhxpDU9z5vUMdiYYXu0Djvq6bEzX mJ/T2IQVUzL1VuP3tYCC2ZBbpwNUnTnzwfwia/NCe0etzdMU2THoXxTjazTWz9GURz ZLOP/zIN/4PnTUXj1eVVzbbEeacPsXfPdGwbQ1pQs36ykLCXOoFeVvrWNhU2ADjmdC IL0sBkAJtsBvQ== Received: from rostedt by gandalf with local (Exim 4.98.2) (envelope-from ) id 1uosj0-000000013dk-3Kq4; Wed, 20 Aug 2025 20:00:14 -0400 Message-ID: <20250821000014.647378837@kernel.org> User-Agent: quilt/0.68 Date: Wed, 20 Aug 2025 20:00:03 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , stable@vger.kernel.org, Pu Lehui Subject: [for-linus][PATCH 3/6] tracing: Limit access to parser->buffer when trace_get_user failed References: <20250821000000.210778097@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Pu Lehui When the length of the string written to set_ftrace_filter exceeds FTRACE_BUFF_MAX, the following KASAN alarm will be triggered: BUG: KASAN: slab-out-of-bounds in strsep+0x18c/0x1b0 Read of size 1 at addr ffff0000d00bd5ba by task ash/165 CPU: 1 UID: 0 PID: 165 Comm: ash Not tainted 6.16.0-g6bcdbd62bd56-dirty Hardware name: linux,dummy-virt (DT) Call trace: show_stack+0x34/0x50 (C) dump_stack_lvl+0xa0/0x158 print_address_description.constprop.0+0x88/0x398 print_report+0xb0/0x280 kasan_report+0xa4/0xf0 __asan_report_load1_noabort+0x20/0x30 strsep+0x18c/0x1b0 ftrace_process_regex.isra.0+0x100/0x2d8 ftrace_regex_release+0x484/0x618 __fput+0x364/0xa58 ____fput+0x28/0x40 task_work_run+0x154/0x278 do_notify_resume+0x1f0/0x220 el0_svc+0xec/0xf0 el0t_64_sync_handler+0xa0/0xe8 el0t_64_sync+0x1ac/0x1b0 The reason is that trace_get_user will fail when processing a string longer than FTRACE_BUFF_MAX, but not set the end of parser->buffer to 0. Then an OOB access will be triggered in ftrace_regex_release-> ftrace_process_regex->strsep->strpbrk. We can solve this problem by limiting access to parser->buffer when trace_get_user failed. Cc: stable@vger.kernel.org Link: https://lore.kernel.org/20250813040232.1344527-1-pulehui@huaweicloud.= com Fixes: 8c9af478c06b ("ftrace: Handle commands when closing set_ftrace_filte= r file") Signed-off-by: Pu Lehui Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 18 ++++++++++++------ kernel/trace/trace.h | 8 +++++++- 2 files changed, 19 insertions(+), 7 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 4283ed4e8f59..8d8935ed416d 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1816,7 +1816,7 @@ int trace_get_user(struct trace_parser *parser, const= char __user *ubuf, =20 ret =3D get_user(ch, ubuf++); if (ret) - return ret; + goto fail; =20 read++; cnt--; @@ -1830,7 +1830,7 @@ int trace_get_user(struct trace_parser *parser, const= char __user *ubuf, while (cnt && isspace(ch)) { ret =3D get_user(ch, ubuf++); if (ret) - return ret; + goto fail; read++; cnt--; } @@ -1848,12 +1848,14 @@ int trace_get_user(struct trace_parser *parser, con= st char __user *ubuf, while (cnt && !isspace(ch) && ch) { if (parser->idx < parser->size - 1) parser->buffer[parser->idx++] =3D ch; - else - return -EINVAL; + else { + ret =3D -EINVAL; + goto fail; + } =20 ret =3D get_user(ch, ubuf++); if (ret) - return ret; + goto fail; read++; cnt--; } @@ -1868,11 +1870,15 @@ int trace_get_user(struct trace_parser *parser, con= st char __user *ubuf, /* Make sure the parsed string always terminates with '\0'. */ parser->buffer[parser->idx] =3D 0; } else { - return -EINVAL; + ret =3D -EINVAL; + goto fail; } =20 *ppos +=3D read; return read; +fail: + trace_parser_fail(parser); + return ret; } =20 /* TODO add a seq_buf_to_buffer() */ diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 1dbf1d3cf2f1..be6654899cae 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1292,6 +1292,7 @@ bool ftrace_event_is_function(struct trace_event_call= *call); */ struct trace_parser { bool cont; + bool fail; char *buffer; unsigned idx; unsigned size; @@ -1299,7 +1300,7 @@ struct trace_parser { =20 static inline bool trace_parser_loaded(struct trace_parser *parser) { - return (parser->idx !=3D 0); + return !parser->fail && parser->idx !=3D 0; } =20 static inline bool trace_parser_cont(struct trace_parser *parser) @@ -1313,6 +1314,11 @@ static inline void trace_parser_clear(struct trace_p= arser *parser) parser->idx =3D 0; } =20 +static inline void trace_parser_fail(struct trace_parser *parser) +{ + parser->fail =3D true; +} + extern int trace_parser_get_init(struct trace_parser *parser, int size); extern void trace_parser_put(struct trace_parser *parser); extern int trace_get_user(struct trace_parser *parser, const char __user *= ubuf, --=20 2.50.1