[for-next][PATCH 09/12] tracing: Fix strncpy warning in trace_events_synth.c

Steven Rostedt
2022-03-12T23:26:33Z

From: Tom Zanussi <zanussi@kernel.org>

0-day reported the strncpy error below:

../kernel/trace/trace_events_synth.c: In function 'last_cmd_set':
../kernel/trace/trace_events_synth.c:65:9: warning: 'strncpy' specified bound depends on the length o\
f the source argument [-Wstringop-truncation]
65 | strncpy(last_cmd, str, strlen(str) + 1);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../kernel/trace/trace_events_synth.c:65:32: note: length computed here
65 | strncpy(last_cmd, str, strlen(str) + 1);
| ^~~~~~~~~~~

There's no reason to use strncpy here, in fact there's no reason to do
anything but a simple kstrdup() (note we don't even need to check for
failure since last_cmod is expected to be either the last cmd string
or NULL, and the containing function is a void return).

Link: https://lkml.kernel.org/r/77deca8cbfd226981b3f1eab203967381e9b5bd9.camel@kernel.org

Fixes: 27c888da9867 ("tracing: Remove size restriction on synthetic event cmd error logging")

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/trace_events_synth.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index fdd79e07e2fc..5e8c07aef071 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -58,11 +58,8 @@ static void last_cmd_set(const char *str)
return;

kfree(last_cmd);
- last_cmd = kzalloc(strlen(str) + 1, GFP_KERNEL);
- if (!last_cmd)
- return;

- strncpy(last_cmd, str, strlen(str) + 1);
+ last_cmd = kstrdup(str, GFP_KERNEL);
}

static void synth_err(u8 err_type, u16 err_pos)
--
2.35.1