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 C514D2D7BF for ; Sun, 24 Aug 2025 13:39:17 +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=1756042758; cv=none; b=l6xYhMu6V9Q3kKqAkToGkB8YVCW35bD3Xo8mGKKySs1rSxAvTjM/5NxM7kCpIZHwMfFJiJUEmWLq0F3r0C0ymJtrKdqbGW2MIe8NypyUyRD3IPKoTlTGuD28lS6goISvN8UAsyGBGj+zhZctlfVhhoRj96j9AOjehT0K4MqwP3g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756042758; c=relaxed/simple; bh=rqRi168T2uHYU5q3rDPDs17stxnlE/OHBVm5g08hJrE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TMBE+u1rP7vmwxsa4ADvJpSxiAN3IgSVy+vk87QwgfdYfR+eZwfpV+/1487Jk/o/W21oWnxqcZ0KFsqW4h0va4cH5jXYJce/bF4pGFpym9QZ2hF8PQDgC9bjILLDa9ndBZz51hGklnPDUxi+Tu/+mcoFGO4Qi+xJ5YJHAX5vhZI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FcOkmkJV; 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="FcOkmkJV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B666BC116B1; Sun, 24 Aug 2025 13:39:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756042757; bh=rqRi168T2uHYU5q3rDPDs17stxnlE/OHBVm5g08hJrE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FcOkmkJVSBUbvA4LyKVKUmbbJLlwLTxEwSVk8P9lHDMmgoc7blrswnlAF8cqYeyPm rcCxXutm4EeKLdPiZIM3pxEVvPYtOxiFwoKqWH8CkITg9+NbgSQgRii+lvLsP+kAL/ bR58jGXKUPN4uRvRy9KFjTVgW+6m0lQqDUms6Z+nlIA8zQSqq7KZ4gW1bbEjN4ZH9u eNWEoh6GdR3E5T6GsI5oPv0eyfe32jXvSH04x8bR3bGo+RoYKo+f7ocziSF4AdnJ5n Lv5kpPKZF7Pq6aGNt9hiPyE2xgD39a1EES0cmOB+yjUYztC4eTnLCVx89EwPR6blqq 9itpIaES5MRbQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Pu Lehui , "Steven Rostedt (Google)" , Sasha Levin Subject: [PATCH 6.6.y 2/2] tracing: Limit access to parser->buffer when trace_get_user failed Date: Sun, 24 Aug 2025 09:39:13 -0400 Message-ID: <20250824133913.2897381-2-sashal@kernel.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250824133913.2897381-1-sashal@kernel.org> References: <2025082330-grimace-stellar-77f2@gregkh> <20250824133913.2897381-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Pu Lehui [ Upstream commit 6a909ea83f226803ea0e718f6e88613df9234d58 ] 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_filter file") Signed-off-by: Pu Lehui Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin --- 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 e915d5a303d5..907e45361939 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1661,7 +1661,7 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf, ret = get_user(ch, ubuf++); if (ret) - return ret; + goto fail; read++; cnt--; @@ -1675,7 +1675,7 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf, while (cnt && isspace(ch)) { ret = get_user(ch, ubuf++); if (ret) - return ret; + goto fail; read++; cnt--; } @@ -1693,12 +1693,14 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf, while (cnt && !isspace(ch) && ch) { if (parser->idx < parser->size - 1) parser->buffer[parser->idx++] = ch; - else - return -EINVAL; + else { + ret = -EINVAL; + goto fail; + } ret = get_user(ch, ubuf++); if (ret) - return ret; + goto fail; read++; cnt--; } @@ -1713,11 +1715,15 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf, /* Make sure the parsed string always terminates with '\0'. */ parser->buffer[parser->idx] = 0; } else { - return -EINVAL; + ret = -EINVAL; + goto fail; } *ppos += read; return read; +fail: + trace_parser_fail(parser); + return ret; } /* TODO add a seq_buf_to_buffer() */ diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index e3afb830fbcc..10a199de0fa5 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1153,6 +1153,7 @@ bool ftrace_event_is_function(struct trace_event_call *call); */ struct trace_parser { bool cont; + bool fail; char *buffer; unsigned idx; unsigned size; @@ -1160,7 +1161,7 @@ struct trace_parser { static inline bool trace_parser_loaded(struct trace_parser *parser) { - return (parser->idx != 0); + return !parser->fail && parser->idx != 0; } static inline bool trace_parser_cont(struct trace_parser *parser) @@ -1174,6 +1175,11 @@ static inline void trace_parser_clear(struct trace_parser *parser) parser->idx = 0; } +static inline void trace_parser_fail(struct trace_parser *parser) +{ + parser->fail = 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, -- 2.50.1