[PATCH] ovl: credential not reverted in ovl_copy_up_flags on error case

[PATCH] ovl: credential not reverted in ovl_copy_up_flags on error case

[youngjun]

In "ovl_copy_up_flags" on disconnected dir case(error case),
credential not reverted.

Fixes: aa3ff3c152ff9("ovl: copy up of disconnected dentries")
Signed-off-by: youngjun <her0gyugyu@gmail.com>
---
 fs/overlayfs/copy_up.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 79dd052c7dbf..53daa54ac859 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -906,8 +906,10 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags)
 	 * In this case, we will copy up lower inode to index dir without
 	 * linking it to upper dir.
 	 */
-	if (WARN_ON(disconnected && d_is_dir(dentry)))
+	if (WARN_ON(disconnected && d_is_dir(dentry))) {
+		revert_creds(old_cred);
 		return -EIO;
+	}
 
 	while (!err) {
 		struct dentry *next;
-- 
2.17.1

Re: [PATCH] ovl: credential not reverted in ovl_copy_up_flags on error case

[Amir Goldstein]

On Mon, Jun 22, 2020 at 8:24 PM youngjun <her0gyugyu@gmail.com> wrote:
>
> In "ovl_copy_up_flags" on disconnected dir case(error case),
> credential not reverted.
>
> Fixes: aa3ff3c152ff9("ovl: copy up of disconnected dentries")
> Signed-off-by: youngjun <her0gyugyu@gmail.com>
> ---
>  fs/overlayfs/copy_up.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
> index 79dd052c7dbf..53daa54ac859 100644
> --- a/fs/overlayfs/copy_up.c
> +++ b/fs/overlayfs/copy_up.c
> @@ -906,8 +906,10 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags)
>          * In this case, we will copy up lower inode to index dir without
>          * linking it to upper dir.
>          */
> -       if (WARN_ON(disconnected && d_is_dir(dentry)))
> +       if (WARN_ON(disconnected && d_is_dir(dentry))) {
> +               revert_creds(old_cred);
>                 return -EIO;
> +       }
>

It is better to move ovl_override_creds() after the WARN_ON test.
which does not require any credentials.

Thanks,
Amir.