From 827a5cb0a0ad3a74426a4e0d12cbc59917785fa2 Mon Sep 17 00:00:00 2001 From: satoru takeuchi Date: Tue, 12 Sep 2017 22:42:52 +0900 Subject: [PATCH] btrfs: prevent to set invalid default subvolid commit 6d6d282932d1a609e60dc4467677e0e863682f57 upstream. `btrfs sub set-default` succeeds to set an ID which isn't corresponding to any fs/file tree. If such the bad ID is set to a filesystem, we can't mount this filesystem without specifying `subvol` or `subvolid` mount options. Fixes: 6ef5ed0d386b ("Btrfs: add ioctl and incompat flag to set the default mount subvol") Cc: Signed-off-by: Satoru Takeuchi Reviewed-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Willy Tarreau --- fs/btrfs/ioctl.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 296cc1b49446..7831e6865f16 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2974,6 +2974,10 @@ static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp) ret = PTR_ERR(new_root); goto out; } + if (!is_fstree(new_root->objectid)) { + ret = -ENOENT; + goto out; + } if (btrfs_root_refs(&new_root->root_item) == 0) { ret = -ENOENT; -- 2.20.1