The function ovl_fill_super() in recently multi-layer support
version will incorrectly return 0 at error handling path and
then cause kernel panic.

This failure can be reproduced by mounting a overlayfs with
upperdir and workdir in different mounts.

And also, If the memory allocation of *lower_mnt* fail, this
function may return an zero either.

This patch fix this problem by setting *err* to proper error
number before jumping to error handling path.

Signed-off-by: hujianyang <hujiany...@huawei.com>
---
 fs/overlayfs/super.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 84f3144..d50e3ed 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -836,6 +836,7 @@ static int ovl_fill_super(struct super_block *sb, void 
*data, int silent)
                if (err)
                        goto out_put_upperpath;

+               err = -EINVAL;
                if (upperpath.mnt != workpath.mnt) {
                        pr_err("overlayfs: workdir and upperdir must reside 
under the same mount\n");
                        goto out_put_workpath;
@@ -894,6 +895,7 @@ static int ovl_fill_super(struct super_block *sb, void 
*data, int silent)
                }
        }

+       err = -ENOMEM;
        ufs->lower_mnt = kcalloc(numlower, sizeof(struct vfsmount *), 
GFP_KERNEL);
        if (ufs->lower_mnt == NULL)
                goto out_put_workdir;
-- 
1.6.0.2

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