From: changbin.du@intel.com
To: rostedt@goodmis.org
Cc: jolsa@redhat.com, peterz@infradead.org, mingo@redhat.com,
alexander.shishkin@linux.intel.com, linux-kernel@vger.kernel.org,
linux-perf-users@vger.kernel.org,
Changbin Du <changbin.du@intel.com>,
stable@vger.kernel.org
Subject: [PATCH 2/3] tracing: make sure the parsed string always terminates with '\0'
Date: Tue, 9 Jan 2018 17:55:47 +0800 [thread overview]
Message-ID: <1515491748-25926-3-git-send-email-changbin.du@intel.com> (raw)
In-Reply-To: <1515491748-25926-1-git-send-email-changbin.du@intel.com>
From: Changbin Du <changbin.du@intel.com>
The parser parse every string into parser.buffer. And some of the callers
assume that parser.buffer contains a C string. So it is dangerous that the
parser returns a unterminated string. The userspace can leverage this to
attack the kernel.
Signed-off-by: Changbin Du <changbin.du@intel.com>
Cc: stable@vger.kernel.org
---
kernel/trace/trace.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 18526a1..e1baca0 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -530,8 +530,6 @@ int trace_pid_write(struct trace_pid_list *filtered_pids,
ubuf += ret;
cnt -= ret;
- parser.buffer[parser.idx] = 0;
-
ret = -EINVAL;
if (kstrtoul(parser.buffer, 0, &val))
break;
@@ -1253,7 +1251,7 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
/* read the non-space input */
while (cnt && !is_space_or_zero(ch)) {
- if (parser->idx < parser->size - 1)
+ if (parser->idx < parser->size - 2)
parser->buffer[parser->idx++] = ch;
else {
ret = -EINVAL;
@@ -1270,9 +1268,11 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
if (is_space_or_zero(ch)) {
parser->buffer[parser->idx] = 0;
parser->cont = false;
- } else if (parser->idx < parser->size - 1) {
+ } else if (parser->idx < parser->size - 2) {
parser->cont = true;
parser->buffer[parser->idx++] = ch;
+ /* Make sure the parsed string always terminates with '\0'. */
+ parser->buffer[parser->idx] = 0;
} else {
ret = -EINVAL;
goto out;
--
2.7.4
next prev parent reply other threads:[~2018-01-09 10:04 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-09 9:55 [PATCH 0/3] tracing: Fix the parser when processing strings w/ or w/o terminated '\0' changbin.du
2018-01-09 9:55 ` [PATCH 1/3] tracing: detect the string termination character when parsing user input string changbin.du
2018-01-09 22:54 ` Steven Rostedt
2018-01-10 3:01 ` Du, Changbin
2018-01-10 4:09 ` Steven Rostedt
2018-01-09 9:55 ` changbin.du [this message]
2018-01-09 23:02 ` [PATCH 2/3] tracing: make sure the parsed string always terminates with '\0' Steven Rostedt
2018-01-10 3:02 ` Du, Changbin
2018-01-10 4:10 ` Steven Rostedt
2018-01-15 10:49 ` Du, Changbin
2018-01-09 9:55 ` [PATCH 3/3] tracing: don't set parser->cont if it has reached the end of input buffer changbin.du
2018-01-09 23:12 ` Steven Rostedt
2018-01-10 3:18 ` Du, Changbin
2018-01-10 4:19 ` Steven Rostedt
2018-01-12 4:05 ` Du, Changbin
2018-01-12 15:31 ` Steven Rostedt
2018-01-14 5:43 ` Du, Changbin
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