linux-kernel - [PATCH 2/4] tracing/filters: Fix double-free of struct filter

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Message-Id: <20230901151039.125186-3-vschneid@redhat.com>
Date:   Fri,  1 Sep 2023 17:10:37 +0200
From:   Valentin Schneider <vschneid@...hat.com>
To:     linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>
Subject: [PATCH 2/4] tracing/filters: Fix double-free of struct filter_pred.mask

When a cpulist filter is found to contain a single CPU, that CPU is saved
as a scalar and the backing cpumask storage is freed.

Also NULL the mask to avoid a double-free once we get down to
free_predicate().

Reported-by: Steven Rostedt <rostedt@...dmis.org>
Signed-off-by: Valentin Schneider <vschneid@...hat.com>
---
 kernel/trace/trace_events_filter.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index c06e1d596f4b9..eb331e8b00b61 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1773,6 +1773,7 @@ static int parse_pred(const char *str, void *data,
 		if (single) {
 			pred->val = cpumask_first(pred->mask);
 			kfree(pred->mask);
+			pred->mask = NULL;
 		}
 
 		if (field->filter_type == FILTER_CPUMASK) {
-- 
2.31.1