linux-kernel - [PATCH] perf top: add concurrent access protection of the SLsmg screen management

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Message-ID: <a91e3943-7ddc-f5c0-a7f5-360f073c20e6@huawei.com>
Date:   Wed, 29 Dec 2021 16:55:19 +0800
From:   yaowenbin <yaowenbin1@...wei.com>
To:     <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
        <mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>,
        <jolsa@...hat.com>, <namhyung@...nel.org>, <yaowenbin1@...wei.com>,
        <linux-kernel@...r.kernel.org>
CC:     <hewenliang4@...wei.com>, <wuxu.wu@...wei.com>
Subject: [PATCH] perf top: add concurrent access protection of the SLsmg
 screen management

When the following command is executed several times, a coredump file is generated.
	$ timeout -k 9 5 perf top -e task-clock
	*******
	*******
	*******
	0.01%  [kernel]                  [k] __do_softirq
	0.01%  libpthread-2.28.so        [.] __pthread_mutex_lock
	0.01%  [kernel]                  [k] __ll_sc_atomic64_sub_return
	double free or corruption (!prev) perf top --sort comm,dso
	timeout: the monitored command dumped core

When we terminate "perf top" using sending signal method, SLsmg_reset_smg
function is called. SLsmg_reset_smg resets the SLsmg screen management routines
by freeing all memory allocated while it was active. However SLsmg_reinit_smg
function maybe be called by another thread. SLsmg_reinit_smg function will
free the same memory accessed by SLsmg_reset_smg functon, thus it results
in double free. SLsmg_reinit_smg function is called already protected by
ui__lock, so we fix the problem by adding pthread_mutex_trylock of ui__lock
when calling SLsmg_reset_smg function.

Signed-off-by: yaowenbin <yaowenbin1@...wei.com>
Signed-off-by: hewenliang <hewenliang4@...wei.com>
Signed-off-by: Wenyu Liu <liuwenyu7@...wei.com>
---
 tools/perf/ui/tui/setup.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/tools/perf/ui/tui/setup.c b/tools/perf/ui/tui/setup.c
index d4ac41679..1fdf92062 100644
--- a/tools/perf/ui/tui/setup.c
+++ b/tools/perf/ui/tui/setup.c
@@ -170,9 +170,11 @@ void ui__exit(bool wait_for_ok)
 				    "Press any key...", 0);

 	SLtt_set_cursor_visibility(1);
-	SLsmg_refresh();
-	SLsmg_reset_smg();
+	if (!pthread_mutex_trylock(&ui__lock)) {
+		SLsmg_refresh();
+		SLsmg_reset_smg();
+		pthread_mutex_unlock(&ui__lock);
+	}
 	SLang_reset_tty();
-
 	perf_error__unregister(&perf_tui_eops);
 }
--
2.27.0