[PATCH 4.19 119/131] tracing: Fix event trigger to accept redundant spaces

Sasha Levin
2020-06-29T20:11:02Z

From: Masami Hiramatsu <mhiramat@kernel.org>

commit 6784beada631800f2c5afd567e5628c843362cee upstream.

Fix the event trigger to accept redundant spaces in
the trigger input.

For example, these return -EINVAL

echo " traceon" > events/ftrace/print/trigger
echo "traceon if common_pid == 0" > events/ftrace/print/trigger
echo "disable_event:kmem:kmalloc " > events/ftrace/print/trigger

But these are hard to find what is wrong.

To fix this issue, use skip_spaces() to remove spaces
in front of actual tokens, and set NULL if there is no
token.

Link: http://lkml.kernel.org/r/159262476352.185015.5261566783045364186.stgit@devnote2

Cc: Tom Zanussi <zanussi@kernel.org>
Cc: stable@vger.kernel.org
Fixes: 85f2b08268c0 ("tracing: Add basic event trigger framework")
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/trace/trace_events_trigger.c | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index 38a2a558e546b..0c3b1551cfca2 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -211,11 +211,17 @@ static int event_trigger_regex_open(struct inode *inode, struct file *file)

static int trigger_process_regex(struct trace_event_file *file, char *buff)
{
- char *command, *next = buff;
+ char *command, *next;
struct event_command *p;
int ret = -EINVAL;

+ next = buff = skip_spaces(buff);
command = strsep(&next, ": \t");
+ if (next) {
+ next = skip_spaces(next);
+ if (!*next)
+ next = NULL;
+ }
command = (command[0] != '!') ? command : command + 1;

mutex_lock(&trigger_cmd_mutex);
@@ -624,8 +630,14 @@ event_trigger_callback(struct event_command *cmd_ops,
int ret;

/* separate the trigger from the filter (t:n [if filter]) */
- if (param && isdigit(param[0]))
+ if (param && isdigit(param[0])) {
trigger = strsep(&param, " \t");
+ if (param) {
+ param = skip_spaces(param);
+ if (!*param)
+ param = NULL;
+ }
+ }

trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);

@@ -1361,6 +1373,11 @@ int event_enable_trigger_func(struct event_command *cmd_ops,
trigger = strsep(&param, " \t");
if (!trigger)
return -EINVAL;
+ if (param) {
+ param = skip_spaces(param);
+ if (!*param)
+ param = NULL;
+ }

system = strsep(&trigger, ":");
if (!trigger)
--
2.25.1