diff options
| author | Wonhyuk Yang <vvghjk1234@gmail.com> | 2022-05-03 14:05:46 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-07-29 17:25:29 +0200 |
| commit | d8413b16feee83d9e00fbfe332ec401726079fe7 (patch) | |
| tree | 4905ab468de6cb721fdf86ec00a57a2688b1112a /kernel | |
| parent | d9777061727b759e999fb04a302ff50a9fd33225 (diff) | |
tracing: Fix return value of trace_pid_write()
[ Upstream commit b27f266f74fbda4ee36c2b2b04d15992860cf23b ]
Setting set_event_pid with trailing whitespace lead to endless write
system calls like below.
$ strace echo "123 " > /sys/kernel/debug/tracing/set_event_pid
execve("/usr/bin/echo", ["echo", "123 "], ...) = 0
...
write(1, "123 \n", 5) = 4
write(1, "\n", 1) = 0
write(1, "\n", 1) = 0
write(1, "\n", 1) = 0
write(1, "\n", 1) = 0
write(1, "\n", 1) = 0
....
This is because, the result of trace_get_user's are not returned when it
read at least one pid. To fix it, update read variable even if
parser->idx == 0.
The result of applied patch is below.
$ strace echo "123 " > /sys/kernel/debug/tracing/set_event_pid
execve("/usr/bin/echo", ["echo", "123 "], ...) = 0
...
write(1, "123 \n", 5) = 5
close(1) = 0
Link: https://lkml.kernel.org/r/20220503050546.288911-1-vvghjk1234@gmail.com
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Baik Song An <bsahn@etri.re.kr>
Cc: Hong Yeon Kim <kimhy@etri.re.kr>
Cc: Taeung Song <taeung@reallinux.co.kr>
Cc: linuxgeek@linuxgeek.io
Cc: stable@vger.kernel.org
Fixes: 4909010788640 ("tracing: Add set_event_pid directory for future use")
Signed-off-by: Wonhyuk Yang <vvghjk1234@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index abbe8489faae..d93f9c59f50e 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -711,13 +711,16 @@ int trace_pid_write(struct trace_pid_list *filtered_pids, pos = 0; ret = trace_get_user(&parser, ubuf, cnt, &pos); - if (ret < 0 || !trace_parser_loaded(&parser)) + if (ret < 0) break; read += ret; ubuf += ret; cnt -= ret; + if (!trace_parser_loaded(&parser)) + break; + ret = -EINVAL; if (kstrtoul(parser.buffer, 0, &val)) break; @@ -743,7 +746,6 @@ int trace_pid_write(struct trace_pid_list *filtered_pids, if (!nr_pids) { /* Cleared the list of pids */ trace_pid_list_free(pid_list); - read = ret; pid_list = NULL; } |