[PATCH] xattr updates (minor, 1/4)

This first patch fixes the copying in of extended attribute
names from userspace in the extended attribute syscalls (a
problem found when using electric fence on the user tools).

Nathan

fs/xattr.c

@@ -67,9 +67,11 @@ setxattr(struct dentry *d, char *name, void *value, size_t size, int flags)
 	if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
 		return -EINVAL;
 
-	if (copy_from_user(kname, name, XATTR_NAME_MAX))
-		return -EFAULT;
-	kname[XATTR_NAME_MAX] = '\0';
+	error = strncpy_from_user(kname, name, sizeof(kname));
+	if (error == 0 || error == sizeof(kname))
+		error = -ERANGE;
+	if (error < 0)
+		return error;
 
 	kvalue = xattr_alloc(size, XATTR_SIZE_MAX);
 	if (IS_ERR(kvalue))
@@ -143,9 +145,11 @@ getxattr(struct dentry *d, char *name, void *value, size_t size)
 	void *kvalue;
 	char kname[XATTR_NAME_MAX + 1];
 
-	if (copy_from_user(kname, name, XATTR_NAME_MAX))
-		return -EFAULT;
-	kname[XATTR_NAME_MAX] = '\0';
+	error = strncpy_from_user(kname, name, sizeof(kname));
+	if (error == 0 || error == sizeof(kname))
+		error = -ERANGE;
+	if (error < 0)
+		return error;
 
 	kvalue = xattr_alloc(size, XATTR_SIZE_MAX);
 	if (IS_ERR(kvalue))
@@ -285,9 +289,11 @@ removexattr(struct dentry *d, char *name)
 	int error;
 	char kname[XATTR_NAME_MAX + 1];
 
-	if (copy_from_user(kname, name, XATTR_NAME_MAX))
-		return -EFAULT;
-	kname[XATTR_NAME_MAX] = '\0';
+	error = strncpy_from_user(kname, name, sizeof(kname));
+	if (error == 0 || error == sizeof(kname))
+		error = -ERANGE;
+	if (error < 0)
+		return error;
 
 	error = -EOPNOTSUPP;
 	if (d->d_inode->i_op && d->d_inode->i_op->removexattr) {