Re: [PATCH] trace: Avoid memory leak in predicate_parse()

From: Steven Rostedt
Date: Tue May 28 2019 - 11:51:46 EST


On Tue, 28 May 2019 17:43:38 +0200
Tomas Bortoli <tomasbortoli@xxxxxxxxx> 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@xxxxxxxxx>
> Reported-by: syzbot+6b8e0fb820e570c59e19@xxxxxxxxxxxxxxxxxxxxxxxxx
> ---
> 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);
> }