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

[Tomas Bortoli]

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.


Signed-off-by: Tomas Bortoli <tomasbort...@gmail.com>
Reported-by: syzbot+6b8e0fb820e570c59...@syzkaller.appspotmail.com
---
 kernel/trace/trace_events_filter.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/trace/trace_events_filter.c 
b/kernel/trace/trace_events_filter.c
index d3e59312ef40..98eafad750d3 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -433,6 +433,8 @@ predicate_parse(const char *str, int nr_parens, int 
nr_preds,
                parse_error(pe, -ENOMEM, 0);
                goto out_free;
        }
+       memset(prog_stack, 0, nr_preds * sizeof(*prog_stack));
+
        inverts = kmalloc_array(nr_preds, sizeof(*inverts), GFP_KERNEL);
        if (!inverts) {
                parse_error(pe, -ENOMEM, 0);
@@ -579,6 +581,8 @@ 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);
 }
-- 
2.11.0