[PATCH] erofs: zero out when listxattr is called with no xattr

[PATCH] erofs: zero out when listxattr is called with no xattr

[Gao Xiang via Linux-erofs]

From: Gao Xiang <gaoxiang25@huawei.com>

As David reported [1], ENODATA returns when attempting
to modify files by using EROFS as a overlayfs lower layer.

The root cause is that listxattr could return unexpected
-ENODATA by mistake for inodes without xattr. That breaks
listxattr return value convention and it can cause copy
up failure when used with overlayfs.

Resolve by zeroing out if no xattr is found for listxattr.

[1] https://lore.kernel.org/r/CAEvUa7nxnby+rxK-KRMA46=exeOMApkDMAV08AjMkkPnTPV4CQ@mail.gmail.com
Fixes: cadf1ccf1b00 ("staging: erofs: add error handling for xattr submodule")
Cc: <stable@vger.kernel.org> # 4.19+
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
 fs/erofs/xattr.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
index a13a78725c57..b766c3ee5fa8 100644
--- a/fs/erofs/xattr.c
+++ b/fs/erofs/xattr.c
@@ -649,6 +649,8 @@ ssize_t erofs_listxattr(struct dentry *dentry,
 	struct listxattr_iter it;
 
 	ret = init_inode_xattrs(d_inode(dentry));
+	if (ret == -ENOATTR)
+		return 0;
 	if (ret)
 		return ret;
 
-- 
2.20.1

Re: [PATCH] erofs: zero out when listxattr is called with no xattr

[Sasha Levin]

Hi,

[This is an automated email]

This commit has been processed because it contains a "Fixes:" tag,
fixing commit: cadf1ccf1b00 ("staging: erofs: add error handling for xattr submodule").

The bot has tested the following trees: v5.4.1, v5.3.14, v4.19.87.

v5.4.1: Build OK!
v5.3.14: Failed to apply! Possible dependencies:
    Unable to calculate

v4.19.87: Failed to apply! Possible dependencies:
    Unable to calculate


NOTE: The patch will not be queued to stable trees until it is upstream.

How should we proceed with this patch?

-- 
Thanks,
Sasha

Re: [PATCH] erofs: zero out when listxattr is called with no xattr

[Gao Xiang]

Hi Sasha,

On Mon, Dec 02, 2019 at 10:13:11PM +0000, Sasha Levin wrote:
> Hi,
> 
> [This is an automated email]
> 
> This commit has been processed because it contains a "Fixes:" tag,
> fixing commit: cadf1ccf1b00 ("staging: erofs: add error handling for xattr submodule").
> 
> The bot has tested the following trees: v5.4.1, v5.3.14, v4.19.87.
> 
> v5.4.1: Build OK!
> v5.3.14: Failed to apply! Possible dependencies:
>     Unable to calculate
> 
> v4.19.87: Failed to apply! Possible dependencies:
>     Unable to calculate

Because of file movement, I'll backport manually then.

Thanks,
Gao Xiang

> 
> 
> NOTE: The patch will not be queued to stable trees until it is upstream.
> 
> How should we proceed with this patch?
> 
> -- 
> Thanks,
> Sasha

Re: [PATCH] erofs: zero out when listxattr is called with no xattr

[Chao Yu]

On 2019/12/1 16:40, Gao Xiang wrote:
> From: Gao Xiang <gaoxiang25@huawei.com>
> 
> As David reported [1], ENODATA returns when attempting
> to modify files by using EROFS as a overlayfs lower layer.
> 
> The root cause is that listxattr could return unexpected
> -ENODATA by mistake for inodes without xattr. That breaks
> listxattr return value convention and it can cause copy
> up failure when used with overlayfs.
> 
> Resolve by zeroing out if no xattr is found for listxattr.
> 
> [1] https://lore.kernel.org/r/CAEvUa7nxnby+rxK-KRMA46=exeOMApkDMAV08AjMkkPnTPV4CQ@mail.gmail.com
> Fixes: cadf1ccf1b00 ("staging: erofs: add error handling for xattr submodule")
> Cc: <stable@vger.kernel.org> # 4.19+
> Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>

Reviewed-by: Chao Yu <yuchao0@huawei.com>

Thanks,