linux-kernel - [PATCH] fs: switch over to vmemdup

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Date:   Mon, 18 Oct 2021 01:01:18 -0700
From:   Qing Wang <wangqing@...o.com>
To:     Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Qing Wang <wangqing@...o.com>
Subject: [PATCH] fs: switch over to vmemdup_user()

This patch fixes the following Coccinelle warning:

fs/xattr.c:563:8-15: WARNING opportunity for vmemdup_user

Use vmemdup_user rather than duplicating its implementation
This is a little bit restricted to reduce false positives

Signed-off-by: Qing Wang <wangqing@...o.com>
---
 fs/xattr.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/fs/xattr.c b/fs/xattr.c
index 5c8c517..288daea
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -560,20 +560,17 @@ setxattr(struct user_namespace *mnt_userns, struct dentry *d,
 	if (size) {
 		if (size > XATTR_SIZE_MAX)
 			return -E2BIG;
-		kvalue = kvmalloc(size, GFP_KERNEL);
-		if (!kvalue)
-			return -ENOMEM;
-		if (copy_from_user(kvalue, value, size)) {
-			error = -EFAULT;
-			goto out;
-		}
+
+		kvalue = vmemdup_user(value, size);
+		if (IS_ERR(kvalue))
+			return ERR_PTR(PTR_ERR(kvalue));
+
 		if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
 		    (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
 			posix_acl_fix_xattr_from_user(mnt_userns, kvalue, size);
 	}
 
 	error = vfs_setxattr(mnt_userns, d, kname, kvalue, size, flags);
-out:
 	kvfree(kvalue);
 
 	return error;
-- 
2.7.4