[PATCH 4/6] switch readdir(2) to unsafe_copy_dirent_name()

[Al Viro]

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

... and the same for its compat counterpart

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
 fs/readdir.c | 30 ++++++++++++++++--------------
 1 file changed, 16 insertions(+), 14 deletions(-)

diff --git a/fs/readdir.c b/fs/readdir.c
index ed6aaad451aa..a9085016a619 100644
--- a/fs/readdir.c
+++ b/fs/readdir.c
@@ -157,17 +157,18 @@ static int fillonedir(struct dir_context *ctx, const char *name, int namlen,
 	}
 	buf->result++;
 	dirent = buf->dirent;
-	if (!access_ok(dirent,
+	if (!user_write_access_begin(dirent,
 			(unsigned long)(dirent->d_name + namlen + 1) -
 				(unsigned long)dirent))
 		goto efault;
-	if (	__put_user(d_ino, &dirent->d_ino) ||
-		__put_user(offset, &dirent->d_offset) ||
-		__put_user(namlen, &dirent->d_namlen) ||
-		__copy_to_user(dirent->d_name, name, namlen) ||
-		__put_user(0, dirent->d_name + namlen))
-		goto efault;
+	unsafe_put_user(d_ino, &dirent->d_ino, efault_end);
+	unsafe_put_user(offset, &dirent->d_offset, efault_end);
+	unsafe_put_user(namlen, &dirent->d_namlen, efault_end);
+	unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end);
+	user_write_access_end();
 	return 0;
+efault_end:
+	user_write_access_end();
 efault:
 	buf->result = -EFAULT;
 	return -EFAULT;
@@ -424,17 +425,18 @@ static int compat_fillonedir(struct dir_context *ctx, const char *name,
 	}
 	buf->result++;
 	dirent = buf->dirent;
-	if (!access_ok(dirent,
+	if (!user_write_access_begin(dirent,
 			(unsigned long)(dirent->d_name + namlen + 1) -
 				(unsigned long)dirent))
 		goto efault;
-	if (	__put_user(d_ino, &dirent->d_ino) ||
-		__put_user(offset, &dirent->d_offset) ||
-		__put_user(namlen, &dirent->d_namlen) ||
-		__copy_to_user(dirent->d_name, name, namlen) ||
-		__put_user(0, dirent->d_name + namlen))
-		goto efault;
+	unsafe_put_user(d_ino, &dirent->d_ino, efault_end);
+	unsafe_put_user(offset, &dirent->d_offset, efault_end);
+	unsafe_put_user(namlen, &dirent->d_namlen, efault_end);
+	unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end);
+	user_write_access_end();
 	return 0;
+efault_end:
+	user_write_access_end();
 efault:
 	buf->result = -EFAULT;
 	return -EFAULT;
-- 
2.11.0