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Subject[PATCH] libceph: protect pending flags in ceph_con_keepalive()
con_flag_test_and_set() sets CON_FLAG_KEEPALIVE_PENDING and
CON_FLAG_WRITE_PENDING flags without protection in ceph_con_keepalive().
It triggers WARN_ON() in clear_standby() if the flags are set after
con_fault() changes connection state to CON_STATE_STANDBY. Move
con_flag_test_and_set() to be called before releasing the lock and store
the condition to check after the critical section.

Reported-by: syzbot+acdeb633f6211ccdf886@syzkaller.appspotmail.com
Signed-off-by: Myungho Jung <mhjungk@gmail.com>
---
net/ceph/messenger.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 2f126eff275d..e15da22d4f37 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -3216,12 +3216,16 @@ void ceph_msg_revoke_incoming(struct ceph_msg *msg)
*/
void ceph_con_keepalive(struct ceph_connection *con)
{
+ bool pending;
+
dout("con_keepalive %p\n", con);
mutex_lock(&con->mutex);
clear_standby(con);
+ pending = (con_flag_test_and_set(con,
+ CON_FLAG_KEEPALIVE_PENDING) == 0 &&
+ con_flag_test_and_set(con, CON_FLAG_WRITE_PENDING) == 0);
mutex_unlock(&con->mutex);
- if (con_flag_test_and_set(con, CON_FLAG_KEEPALIVE_PENDING) == 0 &&
- con_flag_test_and_set(con, CON_FLAG_WRITE_PENDING) == 0)
+ if (pending)
queue_con(con);
}
EXPORT_SYMBOL(ceph_con_keepalive);
--
2.17.1
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