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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@huawei.com>
Signed-off-by: hewenliang <hewenliang4@huawei.com>
Signed-off-by: Wenyu Liu <liuwenyu7@huawei.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
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