btrfs: verify subvolid mount parameter

We aren't verifying the parameter passed to the subvolid mount option,
so we won't report and fail the mount if a junk value is specified for
example, -o subvolid=abc.
This patch verifies the subvolid option with match_u64.

Up to now the memparse function accepts the K/M/G/ suffixes, that are
usually meant for size values and do not make sense for a subvolume it.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 5d752f7..07bc2bf 100644 (file)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -914,8 +914,8 @@ static int btrfs_parse_subvol_options(const char *options, fmode_t flags,
 {
        substring_t args[MAX_OPT_ARGS];
        char *opts, *orig, *p;
-       char *num = NULL;
        int error = 0;
+       u64 subvolid;
 
        if (!options)
                return 0;
@@ -945,18 +945,15 @@ static int btrfs_parse_subvol_options(const char *options, fmode_t flags,
                        }
                        break;
                case Opt_subvolid:
-                       num = match_strdup(&args[0]);
-                       if (num) {
-                               *subvol_objectid = memparse(num, NULL);
-                               kfree(num);
-                               /* we want the original fs_tree */
-                               if (!*subvol_objectid)
-                                       *subvol_objectid =
-                                               BTRFS_FS_TREE_OBJECTID;
-                       } else {
-                               error = -EINVAL;
+                       error = match_u64(&args[0], &subvolid);
+                       if (error)
                                goto out;
-                       }
+
+                       /* we want the original fs_tree */
+                       if (subvolid == 0)
+                               subvolid = BTRFS_FS_TREE_OBJECTID;
+
+                       *subvol_objectid = subvolid;
                        break;
                case Opt_subvolrootid:
                        pr_warn("BTRFS: 'subvolrootid' mount option is deprecated and has no effect\n");