4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Konstantin Khorenko <khorenko@xxxxxxxxxxxxx>
[ Upstream commit 826d7bc9f013d01e92997883d2fd0c25f4af1f1c ]
If the flock owner process is dead and its pid has been already freed,
pid translation won't work, but we still want to show flock owner pid
number when expecting /proc/$PID/fdinfo/$FD in init pidns.
Reproducer:
process A process A1 process A2
fork()--------->
exit() open()
flock()
fork()--------->
exit() sleep()
Before the patch:
================
(root@vz7)/: cat /proc/${PID_A2}/fdinfo/3
pos: 4
flags: 02100002
mnt_id: 257
lock: (root@vz7)/:
After the patch:
===============
(root@vz7)/:cat /proc/${PID_A2}/fdinfo/3
pos: 4
flags: 02100002
mnt_id: 295
lock: 1: FLOCK ADVISORY WRITE ${PID_A1} b6:f8a61:529946 0 EOF
Fixes: 9d5b86ac13c5 ("fs/locks: Remove fl_nspid and use fs-specific l_pid for remote locks")
Signed-off-by: Konstantin Khorenko <khorenko@xxxxxxxxxxxxx>
Acked-by: Andrey Vagin <avagin@xxxxxxxxxx>
Reviewed-by: Benjamin Coddington <bcodding@xxxxxxxxxx>
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/locks.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -2074,6 +2074,13 @@ static pid_t locks_translate_pid(struct
return -1;
if (IS_REMOTELCK(fl))
return fl->fl_pid;
+ /*
+ * If the flock owner process is dead and its pid has been already
+ * freed, the translation below won't work, but we still want to show
+ * flock owner pid number in init pidns.
+ */
+ if (ns == &init_pid_ns)
+ return (pid_t)fl->fl_pid;
rcu_read_lock();
pid = find_pid_ns(fl->fl_pid, &init_pid_ns);
