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Message-ID: <20230406025329.1888-1-laihangliang1@huawei.com>
Date: Thu, 6 Apr 2023 10:53:29 +0800
From: Hangliang Lai <laihangliang1@...wei.com>
To: <namhyung@...nel.org>
CC: <acme@...nel.org>, <adrian.hunter@...el.com>,
<alexander.shishkin@...ux.intel.com>, <brauner@...nel.org>,
<hewenliang4@...wei.com>, <irogers@...gle.com>, <jolsa@...nel.org>,
<laihangliang1@...wei.com>, <linfeilong@...wei.com>,
<linux-kernel@...r.kernel.org>, <linux-perf-users@...r.kernel.org>,
<liuwenyu7@...wei.com>, <mark.rutland@....com>, <mingo@...hat.com>,
<yeyunfeng@...wei.com>
Subject: [PATCH v2] perf top: expand the range of multithreaded phase
In __cmd_top, perf_set_multithreaded is used to enable pthread_rwlock, thus
donw_read and down_write can work to handle concurrency problems. Then top
use perf_set_singlethreaded and switch to single threaded phase, assuming
that no thread concurrency will happen later.
However, a UAF problem could occur in perf top in single threaded phase,
The concurrent procedure is like this:
display_thread process_thread
-------------- --------------
thread__comm_len
-> thread__comm_str
-> __thread__comm_str(thread)
thread__delete
-> comm__free
-> comm_str__put
-> zfree(&cs->str)
-> thread->comm_len = strlen(comm);
Since in single thread phase, perf_singlethreaded is true, down_read and
down_write can not work to avoid concurrency problems.
This patch put perf_set_singlethreaded to the function tail to expand the
multithreaded phase range, make display_thread and process_thread run
safe.
Signed-off-by: Hangliang Lai <laihangliang1@...wei.com>
Reviewed-by: Yunfeng Ye <yeyunfeng@...wei.com>
---
v1 -> v2
- Since perf top is always multi-threaded, remove top->nr_threads_synthesize judgment.
tools/perf/builtin-top.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index d4b5b02bab73..a18db1ee87fa 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1242,8 +1242,7 @@ static int __cmd_top(struct perf_top *top)
if (perf_session__register_idle_thread(top->session) < 0)
return ret;
- if (top->nr_threads_synthesize > 1)
- perf_set_multithreaded();
+ perf_set_multithreaded();
init_process_thread(top);
@@ -1273,9 +1272,6 @@ static int __cmd_top(struct perf_top *top)
top->evlist->core.threads, true, false,
top->nr_threads_synthesize);
- if (top->nr_threads_synthesize > 1)
- perf_set_singlethreaded();
-
if (perf_hpp_list.socket) {
ret = perf_env__read_cpu_topology_map(&perf_env);
if (ret < 0) {
@@ -1352,6 +1348,9 @@ static int __cmd_top(struct perf_top *top)
out_join_thread:
cond_signal(&top->qe.cond);
pthread_join(thread_process, NULL);
+
+ perf_set_singlethreaded();
+
return ret;
}
--
2.33.0
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