lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Date:   Wed, 15 Jul 2020 15:41:07 -0700
From:   Stanislav Fomichev <>
        Stanislav Fomichev <>,
        Andrii Nakryiko <>
Subject: [PATCH bpf-next] selftests/bpf: fix possible hang in sockopt_inherit

Andrii reported that sockopt_inherit occasionally hangs up on 5.5 kernel [0].
This can happen if server_thread runs faster than the main thread.
In that case, pthread_cond_wait will wait forever because
pthread_cond_signal was executed before the main thread was blocking.
Let's move pthread_mutex_lock up a bit to make sure server_thread
runs strictly after the main thread goes to sleep.

(Not sure why this is 5.5 specific, maybe scheduling is less
deterministic? But I was able to confirm that it does indeed
happen in a VM.)


Reported-by: Andrii Nakryiko <>
Signed-off-by: Stanislav Fomichev <>
 tools/testing/selftests/bpf/prog_tests/sockopt_inherit.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/sockopt_inherit.c b/tools/testing/selftests/bpf/prog_tests/sockopt_inherit.c
index 8547ecbdc61f..ec281b0363b8 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockopt_inherit.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockopt_inherit.c
@@ -193,11 +193,10 @@ static void run_test(int cgroup_fd)
 	if (CHECK_FAIL(server_fd < 0))
 		goto close_bpf_object;
+	pthread_mutex_lock(&server_started_mtx);
 	if (CHECK_FAIL(pthread_create(&tid, NULL, server_thread,
 				      (void *)&server_fd)))
 		goto close_server_fd;
-	pthread_mutex_lock(&server_started_mtx);
 	pthread_cond_wait(&server_started, &server_started_mtx);

Powered by blists - more mailing lists