ovl: check lowerdir amount for non-upper mount

[sfrench/cifs-2.6.git] / fs / overlayfs / super.c

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index b90952f528b1cdf7414e49b5613e439d6b89fb7a..edbb3ebcdaadb661befd7af7d8476ab37c3beda0 100644 (file)
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -615,6 +615,7 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config)
                        break;
 
                default:
+                       pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);
                        return -EINVAL;
                }
        }
@@ -869,8 +870,14 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 
        err = -EINVAL;
        stacklen = ovl_split_lowerdirs(lowertmp);
-       if (stacklen > OVL_MAX_STACK)
+       if (stacklen > OVL_MAX_STACK) {
+               pr_err("overlayfs: too many lower directries, limit is %d\n",
+                      OVL_MAX_STACK);
                goto out_free_lowertmp;
+       } else if (!ufs->config.upperdir && stacklen == 1) {
+               pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n");
+               goto out_free_lowertmp;
+       }
 
        stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL);
        if (!stack)