2018-03-28 11:56:12

by Dan Carpenter

Subject: [PATCH] tracing: Uninitialized variable in create_tracing_map_fields()

Smatch complains that idx can be used uninitialized when we check if
(idx < 0). It has to be the first iteration through the loop and the
HIST_FIELD_FL_STACKTRACE bit has to be clear and the HIST_FIELD_FL_VAR
bit has to be set to reach the bug.

Fixes: 30350d65ac56 ("tracing: Add variable support to hist triggers")
Signed-off-by: Dan Carpenter <[email protected]>

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 4f027642ceef..6aceee287d07 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -4411,7 +4411,7 @@ static int create_tracing_map_fields(struct hist_trigger_data *hist_data)
struct tracing_map *map = hist_data->map;
struct ftrace_event_field *field;
struct hist_field *hist_field;
- int i, idx;
+ int i, idx = 0;

for_each_hist_field(i, hist_data) {
hist_field = hist_data->fields[i];

2018-03-28 14:07:00

by Tom Zanussi

Subject: Re: [PATCH] tracing: Uninitialized variable in create_tracing_map_fields()

Hi Dan,

On Wed, 2018-03-28 at 14:48 +0300, Dan Carpenter wrote:
> Smatch complains that idx can be used uninitialized when we check if
> (idx < 0). It has to be the first iteration through the loop and the
> HIST_FIELD_FL_STACKTRACE bit has to be clear and the HIST_FIELD_FL_VAR
> bit has to be set to reach the bug.
>
> Fixes: 30350d65ac56 ("tracing: Add variable support to hist triggers")
> Signed-off-by: Dan Carpenter <[email protected]>
>
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index 4f027642ceef..6aceee287d07 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -4411,7 +4411,7 @@ static int create_tracing_map_fields(struct hist_trigger_data *hist_data)
> struct tracing_map *map = hist_data->map;
> struct ftrace_event_field *field;
> struct hist_field *hist_field;
> - int i, idx;
> + int i, idx = 0;
>
> for_each_hist_field(i, hist_data) {
> hist_field = hist_data->fields[i];

Yes, this should definitely be initialized to 0, thanks for the patch!

Acked-by: Tom Zanussi <[email protected]>

2018-04-02 15:53:54

by Steven Rostedt

Subject: Re: [PATCH] tracing: Uninitialized variable in create_tracing_map_fields()

On Wed, 28 Mar 2018 09:04:40 -0500
Tom Zanussi <[email protected]> wrote:

> Yes, this should definitely be initialized to 0, thanks for the patch!
>
> Acked-by: Tom Zanussi <[email protected]>

Thanks, I applied it and will push to git after it has succeeded in
testing.

-- Steve