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

[Al Viro]

From: Al Viro <v...@zeniv.linux.org.uk>

... and the same for its compat counterpart

Signed-off-by: Al Viro <v...@zeniv.linux.org.uk>
---
 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