nfs: Enclose hostname in brackets when needed in nfs_do_root_mount

When hostname contains colon (e.g. when it is an IPv6 address) it needs
to be enclosed in brackets to make parsing of NFS device string possible.
Fix nfs_do_root_mount() to enclose hostname properly when needed. NFS code
actually does not need this as it does not parse the string passed by
nfs_do_root_mount() but the device string is exposed to userspace in
/proc/mounts.

CC: Josh Boyer <jwboyer@redhat.com>
CC: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 37412f706b32..1e6715f0616c 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -2767,11 +2767,15 @@ static struct vfsmount *nfs_do_root_mount(struct file_system_type *fs_type,
         char *root_devname;
         size_t len;
 
-        len = strlen(hostname) + 3;
+        len = strlen(hostname) + 5;
         root_devname = kmalloc(len, GFP_KERNEL);
         if (root_devname == NULL)
                 return ERR_PTR(-ENOMEM);
-        snprintf(root_devname, len, "%s:/", hostname);
+        /* Does hostname needs to be enclosed in brackets? */
+        if (strchr(hostname, ':'))
+                snprintf(root_devname, len, "[%s]:/", hostname);
+        else
+                snprintf(root_devname, len, "%s:/", hostname);
         root_mnt = vfs_kern_mount(fs_type, flags, root_devname, data);
         kfree(root_devname);
         return root_mnt;