diff options
| author | Greg Kurz <groug@kaod.org> | 2021-06-04 18:11:51 +0200 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2021-06-09 15:33:40 +0200 |
| commit | e3a43f2a95393000778f8f302d48795add2fc4a8 (patch) | |
| tree | 31fe77230b36172d8e0c898c9137c596d8041843 /fs/fuse | |
| parent | d92d88f0568e97c437eeb79d9c9609bd8277406f (diff) | |
fuse: Fix crash if superblock of submount gets killed early
As soon as fuse_dentry_automount() does up_write(&sb->s_umount), the
superblock can theoretically be killed. If this happens before the
submount was added to the &fc->mounts list, fuse_mount_remove() later
crashes in list_del_init() because it assumes the submount to be
already there.
Add the submount before dropping sb->s_umount to fix the inconsistency.
It is okay to nest fc->killsb under sb->s_umount, we already do this
on the ->kill_sb() path.
Signed-off-by: Greg Kurz <groug@kaod.org>
Fixes: bf109c64040f ("fuse: implement crossmounts")
Cc: stable@vger.kernel.org # v5.10+
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/fuse')
| -rw-r--r-- | fs/fuse/dir.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index 01559061cbfb..3fd1b71e546b 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -346,15 +346,15 @@ static struct vfsmount *fuse_dentry_automount(struct path *path) goto out_put_sb; } + down_write(&fc->killsb); + list_add_tail(&fm->fc_entry, &fc->mounts); + up_write(&fc->killsb); + sb->s_flags |= SB_ACTIVE; fsc->root = dget(sb->s_root); /* We are done configuring the superblock, so unlock it */ up_write(&sb->s_umount); - down_write(&fc->killsb); - list_add_tail(&fm->fc_entry, &fc->mounts); - up_write(&fc->killsb); - /* Create the submount */ mnt = vfs_create_mount(fsc); if (IS_ERR(mnt)) { |