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

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Message-Id: <20190528154338.29976-1-tomasbortoli@gmail.com>
Date:   Tue, 28 May 2019 17:43:38 +0200
From:   Tomas Bortoli <tomasbortoli@...il.com>
To:     rostedt@...dmis.org
Cc:     linux-kernel@...r.kernel.org, mingo@...hat.com,
        Tomas Bortoli <tomasbortoli@...il.com>
Subject: [PATCH] trace: Avoid memory leak in predicate_parse()

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 <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);
 }
-- 
2.11.0