linux-kernel - Re: [PATCH] perf probe: Fix uninitialized variable

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Message-Id: <20241211075510.ea7924b5b80bf0d95993086b@kernel.org>
Date: Wed, 11 Dec 2024 07:55:10 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: James Clark <james.clark@...aro.org>
Cc: linux-perf-users@...r.kernel.org, namhyung@...nel.org, acme@...nel.org,
 Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, Mark
 Rutland <mark.rutland@....com>, Alexander Shishkin
 <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, Ian
 Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>,
 "Liang, Kan" <kan.liang@...ux.intel.com>, "Masami Hiramatsu (Google)"
 <mhiramat@...nel.org>, Leo Yan <leo.yan@....com>, Dima Kogan
 <dima@...retsauce.net>, "Dr. David Alan Gilbert" <linux@...blig.org>,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf probe: Fix uninitialized variable

Hi,

On Mon,  9 Dec 2024 17:12:21 +0000
James Clark <james.clark@...aro.org> wrote:

> Since the linked fixes: commit, err is returned uninitialized due to the
> removal of "return 0". Initialize err to fix it, and rename err to out
> to avoid confusion because buf is still supposed to be freed in non
> error cases.
> 
> This fixes the following intermittent test failure on release builds:
> 
>  $ perf test "testsuite_probe"
>  ...
>  -- [ FAIL ] -- perf_probe :: test_invalid_options :: mutually exclusive options :: -L foo -V bar (output regexp parsing)
>  Regexp not found: \"Error: switch .+ cannot be used with switch .+\"
>  ...
> 
> Fixes: 080e47b2a237 ("perf probe: Introduce quotation marks support")
> Signed-off-by: James Clark <james.clark@...aro.org>
> ---
>  tools/perf/util/probe-event.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 6d51a4c98ad7..35af6570cf9b 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -1370,7 +1370,7 @@ int parse_line_range_desc(const char *arg, struct line_range *lr)
>  {
>  	char *buf = strdup(arg);
>  	char *p;
> -	int err;
> +	int err = 0;

I think only this is required, and others are just cleanups by renaming
err -> out (usually for-next).
But Arnaldo is OK to combine these changes, I'm OK too.

Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

Thank you,

>  
>  	if (!buf)
>  		return -ENOMEM;
> @@ -1383,20 +1383,20 @@ int parse_line_range_desc(const char *arg, struct line_range *lr)
>  		if (p == buf) {
>  			semantic_error("No file/function name in '%s'.\n", p);
>  			err = -EINVAL;
> -			goto err;
> +			goto out;
>  		}
>  		*(p++) = '\0';
>  
>  		err = parse_line_num(&p, &lr->start, "start line");
>  		if (err)
> -			goto err;
> +			goto out;
>  
>  		if (*p == '+' || *p == '-') {
>  			const char c = *(p++);
>  
>  			err = parse_line_num(&p, &lr->end, "end line");
>  			if (err)
> -				goto err;
> +				goto out;
>  
>  			if (c == '+') {
>  				lr->end += lr->start;
> @@ -1416,11 +1416,11 @@ int parse_line_range_desc(const char *arg, struct line_range *lr)
>  		if (lr->start > lr->end) {
>  			semantic_error("Start line must be smaller"
>  				       " than end line.\n");
> -			goto err;
> +			goto out;
>  		}
>  		if (*p != '\0') {
>  			semantic_error("Tailing with invalid str '%s'.\n", p);
> -			goto err;
> +			goto out;
>  		}
>  	}
>  
> @@ -1431,7 +1431,7 @@ int parse_line_range_desc(const char *arg, struct line_range *lr)
>  			lr->file = strdup_esq(p);
>  			if (lr->file == NULL) {
>  				err = -ENOMEM;
> -				goto err;
> +				goto out;
>  			}
>  		}
>  		if (*buf != '\0')
> @@ -1439,7 +1439,7 @@ int parse_line_range_desc(const char *arg, struct line_range *lr)
>  		if (!lr->function && !lr->file) {
>  			semantic_error("Only '@*' is not allowed.\n");
>  			err = -EINVAL;
> -			goto err;
> +			goto out;
>  		}
>  	} else if (strpbrk_esq(buf, "/."))
>  		lr->file = strdup_esq(buf);
> @@ -1448,10 +1448,10 @@ int parse_line_range_desc(const char *arg, struct line_range *lr)
>  	else {	/* Invalid name */
>  		semantic_error("'%s' is not a valid function name.\n", buf);
>  		err = -EINVAL;
> -		goto err;
> +		goto out;
>  	}
>  
> -err:
> +out:
>  	free(buf);
>  	return err;
>  }
> -- 
> 2.34.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>