Overlayfs should be mounted read-only when upper fs is r/o or nonexistend. But now it can be remounted read-write and this can causes kernel panic. So we should prevent read-write remount when the above situation.
Signed-off-by: Seunghun Lee <[email protected]> --- fs/overlayfs/super.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 84f3144..8944651 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -522,10 +522,21 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) return 0; } +static int ovl_remount(struct super_block *sb, int *flags, char *data) +{ + struct ovl_fs *ufs = sb->s_fs_info; + + if (!ufs->upper_mnt || (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY)) + *flags |= MS_RDONLY; + + return 0; +} + static const struct super_operations ovl_super_operations = { .put_super = ovl_put_super, .statfs = ovl_statfs, .show_options = ovl_show_options, + .remount_fs = ovl_remount, }; enum { -- 2.1.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
