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authorIlya Dryomov <idryomov@gmail.com>2019-01-14 21:13:10 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-02-20 10:13:20 +0100
commit2e9e4e1590d2f9e572b6a72991ba6ca54019374c (patch)
treeae593498cbba4d38c69e763e875587fbe2f4d326
parent1793dc65ee85f96ce2ddcdb586e98214ac0dc474 (diff)
libceph: avoid KEEPALIVE_PENDING races in ceph_con_keepalive()
commit 4aac9228d16458cedcfd90c7fb37211cf3653ac3 upstream. con_fault() can transition the connection into STANDBY right after ceph_con_keepalive() clears STANDBY in clear_standby(): libceph user thread ceph-msgr worker ceph_con_keepalive() mutex_lock(&con->mutex) clear_standby(con) mutex_unlock(&con->mutex) mutex_lock(&con->mutex) con_fault() ... if KEEPALIVE_PENDING isn't set set state to STANDBY ... mutex_unlock(&con->mutex) set KEEPALIVE_PENDING set WRITE_PENDING This triggers warnings in clear_standby() when either ceph_con_send() or ceph_con_keepalive() get to clearing STANDBY next time. I don't see a reason to condition queue_con() call on the previous value of KEEPALIVE_PENDING, so move the setting of KEEPALIVE_PENDING into the critical section -- unlike WRITE_PENDING, KEEPALIVE_PENDING could have been a non-atomic flag. Reported-by: syzbot+acdeb633f6211ccdf886@syzkaller.appspotmail.com Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Tested-by: Myungho Jung <mhjungk@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/ceph/messenger.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index ad3c9e96a275..3e6897efe1eb 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -3181,9 +3181,10 @@ void ceph_con_keepalive(struct ceph_connection *con)
dout("con_keepalive %p\n", con);
mutex_lock(&con->mutex);
clear_standby(con);
+ con_flag_set(con, CON_FLAG_KEEPALIVE_PENDING);
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 (con_flag_test_and_set(con, CON_FLAG_WRITE_PENDING) == 0)
queue_con(con);
}
EXPORT_SYMBOL(ceph_con_keepalive);