linux-kernel - [PATCH 1/1] perf callchain: Use zfree() to avoid possibly accessing dangling pointers

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Message-ID: <ZjmcGobQ8E52EyjJ@x1>
Date: Tue, 7 May 2024 00:12:26 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Adrian Hunter <adrian.hunter@...el.com>, Jiri Olsa <jolsa@...nel.org>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-perf-users@...r.kernel.org
Subject: [PATCH 1/1] perf callchain: Use zfree() to avoid possibly accessing
 dangling pointers

When freeing a->b it is good practice to set a->b to NULL using
zfree(&a->b) so that when we have a bug where a reference to a freed 'a'
pointer is kept somewhere, we can more quickly cause a segfault if some
code tries to use a->b.

Convert one such case in the callchain code.

Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Ian Rogers <irogers@...gle.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Kan Liang <kan.liang@...ux.intel.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/callchain.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
index 68feed8718096f78..1730b852a947400f 100644
--- a/tools/perf/util/callchain.c
+++ b/tools/perf/util/callchain.c
@@ -606,7 +606,7 @@ fill_node(struct callchain_node *node, struct callchain_cursor *cursor)
 					call->brtype_stat = zalloc(sizeof(*call->brtype_stat));
 					if (!call->brtype_stat) {
 						perror("not enough memory for the code path branch statistics");
-						free(call->brtype_stat);
+						zfree(&call->brtype_stat);
 						return -ENOMEM;
 					}
 				}
-- 
2.44.0