linux-kernel - [PATCH] f2fs: correct removexattr behavior for null valued extended attribute

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Date:   Sat, 20 Jan 2018 15:46:33 +0800
From:   Chao Yu <chao@...nel.org>
To:     jaegeuk@...nel.org
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Chao Yu <yuchao0@...wei.com>,
        Daeho Jeong <daeho.jeong@...sung.com>,
        Youngjin Gil <youngjin.gil@...sung.com>
Subject: [PATCH] f2fs: correct removexattr behavior for null valued extended attribute

From: Daeho Jeong <daeho.jeong@...sung.com>

__vfs_removexattr() transfers "NULL" value to the setxattr handler of
the f2fs filesystem in order to remove the extended attribute. But,
__f2fs_setxattr() just ignores the removal request when the value of
the extended attribute is already NULL. We have to remove the extended
attribute itself even if the value of that is already NULL.

We can reporduce this bug with the below:

1. touch file
2. setfattr -n "user.foo" file
3. setfattr -x "user.foo" file
4. getfattr -d file
> user.foo

Signed-off-by: Daeho Jeong <daeho.jeong@...sung.com>
Signed-off-by: Youngjin Gil <youngjin.gil@...sung.com>
Tested-by: Hobin Woo <hobin.woo@...sung.com>
Tested-by: Chao Yu <yuchao0@...wei.com>
Reviewed-by: Chao Yu <yuchao0@...wei.com>
Signed-off-by: Chao Yu <yuchao0@...wei.com>
---
 fs/f2fs/xattr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
index 600162f4ddbf..ae2dfa709f5d 100644
--- a/fs/f2fs/xattr.c
+++ b/fs/f2fs/xattr.c
@@ -600,7 +600,7 @@ static int __f2fs_setxattr(struct inode *inode, int index,
 			goto exit;
 		}
 
-		if (f2fs_xattr_value_same(here, value, size))
+		if (value && f2fs_xattr_value_same(here, value, size))
 			goto exit;
 	} else if ((flags & XATTR_REPLACE)) {
 		error = -ENODATA;
-- 
2.14.1.145.gb3622a4ee