[PATCH] perf lock: Fix a memory leak on an error path

[PATCH] perf lock: Fix a memory leak on an error path

[zhaimingbing]

if a strdup-ed string is NULL,the allocated memory needs freeing.

Signed-off-by: zhaimingbing <zhaimingbing@cmss.chinamobile.com>
---
 tools/perf/builtin-lock.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
index b141f2134..086041bcb 100644
--- a/tools/perf/builtin-lock.c
+++ b/tools/perf/builtin-lock.c
@@ -2228,8 +2228,10 @@ static int __cmd_record(int argc, const char **argv)
 		else
 			ev_name = strdup(contention_tracepoints[j].name);
 
-		if (!ev_name)
+		if (!ev_name) {
+			free(rec_argv);
 			return -ENOMEM;
+		}
 
 		rec_argv[i++] = "-e";
 		rec_argv[i++] = ev_name;
-- 
2.33.0

Re: [PATCH] perf lock: Fix a memory leak on an error path

[Peter Zijlstra]

On Fri, Nov 24, 2023 at 05:26:57PM +0800, zhaimingbing wrote:
> if a strdup-ed string is NULL,the allocated memory needs freeing.
> 
> Signed-off-by: zhaimingbing <zhaimingbing@cmss.chinamobile.com>
> ---
>  tools/perf/builtin-lock.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
> index b141f2134..086041bcb 100644
> --- a/tools/perf/builtin-lock.c
> +++ b/tools/perf/builtin-lock.c
> @@ -2228,8 +2228,10 @@ static int __cmd_record(int argc, const char **argv)
>  		else
>  			ev_name = strdup(contention_tracepoints[j].name);
>  
> -		if (!ev_name)
> +		if (!ev_name) {
> +			free(rec_argv);
>  			return -ENOMEM;
> +		}

Isn't this an error path straight into exit?

Re: [PATCH] perf lock: Fix a memory leak on an error path

[Ingo Molnar]

* Peter Zijlstra <peterz@infradead.org> wrote:

> On Fri, Nov 24, 2023 at 05:26:57PM +0800, zhaimingbing wrote:
> > if a strdup-ed string is NULL,the allocated memory needs freeing.
> > 
> > Signed-off-by: zhaimingbing <zhaimingbing@cmss.chinamobile.com>
> > ---
> >  tools/perf/builtin-lock.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
> > index b141f2134..086041bcb 100644
> > --- a/tools/perf/builtin-lock.c
> > +++ b/tools/perf/builtin-lock.c
> > @@ -2228,8 +2228,10 @@ static int __cmd_record(int argc, const char **argv)
> >  		else
> >  			ev_name = strdup(contention_tracepoints[j].name);
> >  
> > -		if (!ev_name)
> > +		if (!ev_name) {
> > +			free(rec_argv);
> >  			return -ENOMEM;
> > +		}
> 
> Isn't this an error path straight into exit?

It increases the quality of implementation if resources are free()d 
consistently regardless of whether the task is going to exit() immediately, 
for example it makes it easier to validate perf for the lack of memory 
leaks with Valgrind.

Thanks,

	Ingo

Re: [PATCH] perf lock: Fix a memory leak on an error path

[Arnaldo Carvalho de Melo]

Em Fri, Nov 24, 2023 at 01:56:35PM +0100, Ingo Molnar escreveu:
> 
> * Peter Zijlstra <peterz@infradead.org> wrote:
> 
> > On Fri, Nov 24, 2023 at 05:26:57PM +0800, zhaimingbing wrote:
> > > if a strdup-ed string is NULL,the allocated memory needs freeing.
> > > 
> > > Signed-off-by: zhaimingbing <zhaimingbing@cmss.chinamobile.com>
> > > ---
> > >  tools/perf/builtin-lock.c | 4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
> > > index b141f2134..086041bcb 100644
> > > --- a/tools/perf/builtin-lock.c
> > > +++ b/tools/perf/builtin-lock.c
> > > @@ -2228,8 +2228,10 @@ static int __cmd_record(int argc, const char **argv)
> > >  		else
> > >  			ev_name = strdup(contention_tracepoints[j].name);
> > >  
> > > -		if (!ev_name)
> > > +		if (!ev_name) {
> > > +			free(rec_argv);
> > >  			return -ENOMEM;
> > > +		}
> > 
> > Isn't this an error path straight into exit?
> 
> It increases the quality of implementation if resources are free()d 
> consistently regardless of whether the task is going to exit() immediately, 
> for example it makes it easier to validate perf for the lack of memory 
> leaks with Valgrind.

I'm taking this positive comment about the patch as an Acked-by, ok?

- Arnaldo