linux-kernel - Re: [PATCH] trace: Avoid memory leak in predicate

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Message-ID: <20190528114821.2302dabd@gandalf.local.home>
Date:   Tue, 28 May 2019 11:48:21 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Tomas Bortoli <tomasbortoli@...il.com>
Cc:     linux-kernel@...r.kernel.org, mingo@...hat.com
Subject: Re: [PATCH] trace: Avoid memory leak in predicate_parse()

On Tue, 28 May 2019 17:43:38 +0200
Tomas Bortoli <tomasbortoli@...il.com> wrote:

> In case of errors, predicate_parse() goes to the out_free label
> to free memory and to return an error code.
> 
> However, predicate_parse() does not free the predicates of the
> temporary prog_stack array, thence leaking them.

Thanks, I applied this and I'm running it through my tests. But just an
FYI, when sending updated patches please add a "v2" to the subject:

 [PATCH v2] tracing: Avoid memory leak in predicate_parse()

That way struggling maintainers like myself don't get confused about
which patch to apply ;-)

Thanks!

-- Steve


> 
> Signed-off-by: Tomas Bortoli <tomasbortoli@...il.com>
> Reported-by: syzbot+6b8e0fb820e570c59e19@...kaller.appspotmail.com
> ---
>  kernel/trace/trace_events_filter.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
> index 05a66493a164..ecfa6f0f1c7e 100644
> --- a/kernel/trace/trace_events_filter.c
> +++ b/kernel/trace/trace_events_filter.c
> @@ -427,7 +427,7 @@ predicate_parse(const char *str, int nr_parens, int nr_preds,
>  	op_stack = kmalloc_array(nr_parens, sizeof(*op_stack), GFP_KERNEL);
>  	if (!op_stack)
>  		return ERR_PTR(-ENOMEM);
> -	prog_stack = kmalloc_array(nr_preds, sizeof(*prog_stack), GFP_KERNEL);
> +	prog_stack = kcalloc(nr_preds, sizeof(*prog_stack), GFP_KERNEL);
>  	if (!prog_stack) {
>  		parse_error(pe, -ENOMEM, 0);
>  		goto out_free;
> @@ -578,6 +578,8 @@ predicate_parse(const char *str, int nr_parens, int nr_preds,
>  out_free:
>  	kfree(op_stack);
>  	kfree(inverts);
> +	for (i = 0; prog_stack[i].pred; i++)
> +		kfree(prog_stack[i].pred);
>  	kfree(prog_stack);
>  	return ERR_PTR(ret);
>  }