`libmount` from util-linux and many softwares in userspace (e.g.
kubelet) did not expect empty string as mount source:
```
$ mount -t tmpfs "" /mnt/tmpfs
$ findmnt /mnt/tmpfs
findmnt: /proc/self/mountinfo: parse error at line 51
$ cat /proc/self/mountinfo | grep -P '\/mnt\/tmpfs'
74 25 0:59 / /mnt/tmpfs rw,relatime shared:38 - tmpfs rw
$ cat /proc/self/mounts | grep -P '\/mnt\/tmpfs'
/mnt/tmpfs tmpfs rw,relatime 0 0
```
`source` field in mounts/mountinfo is empty, which breaks a lot of
mounts/mountinfo parsers.
This fixes issues in parsing when user uses empty string as mount
source.
Cc: Karel Zak <kzak@xxxxxxxxxx>
Signed-off-by: Yecheng Fu <cofyc.jackson@xxxxxxxxx>
---
PATCH v2 updates `show_vfsstat()` too.
fs/proc_namespace.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c
index 3f1190d..24591b8 100644
--- a/fs/proc_namespace.c
+++ b/fs/proc_namespace.c
@@ -104,7 +104,7 @@ static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
if (err)
goto out;
} else {
- mangle(m, r->mnt_devname ? r->mnt_devname : "none");
+ mangle(m, (r->mnt_devname && r->mnt_devname[0] != '\0') ? r->mnt_devname : "none");
}
seq_putc(m, ' ');
/* mountpoints outside of chroot jail will give SEQ_SKIP on this */
@@ -174,7 +174,7 @@ static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
if (err)
goto out;
} else {
- mangle(m, r->mnt_devname ? r->mnt_devname : "none");
+ mangle(m, (r->mnt_devname && r->mnt_devname[0] != '\0') ? r->mnt_devname : "none");
}
seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
err = show_sb_opts(m, sb);
@@ -202,7 +202,7 @@ static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
if (err)
goto out;
} else {
- if (r->mnt_devname) {
+ if (r->mnt_devname && r->mnt_devname[0] != '\0') {
seq_puts(m, "device ");
mangle(m, r->mnt_devname);
} else
--
Yecheng Fu
