f2fs: fix possible data corruption in f2fs_write_begin()

commit 9234f3190bf8b25b11b105191d408ac50a107948 upstream.

f2fs_write_begin() doesn't initialize the 'dn' variable if the inode has
inline data. However it uses its contents to decide whether it should
just zero out the page or load data to it. Thus if we are unlucky we can
zero out page contents instead of loading inline data into a page.

CC: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 76de83e25a891d8cf85c4b84d2641dbf414a77e6..0da8365fa74e4dc6fef830119fbd3fc4ca57072f 100644 (file)
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1002,21 +1002,19 @@ inline_data:
                goto out;
        }
 
-       if (dn.data_blkaddr == NEW_ADDR) {
+       if (f2fs_has_inline_data(inode)) {
+               err = f2fs_read_inline_data(inode, page);
+               if (err) {
+                       page_cache_release(page);
+                       goto fail;
+               }
+       } else if (dn.data_blkaddr == NEW_ADDR) {
                zero_user_segment(page, 0, PAGE_CACHE_SIZE);
        } else {
-               if (f2fs_has_inline_data(inode)) {
-                       err = f2fs_read_inline_data(inode, page);
-                       if (err) {
-                               page_cache_release(page);
-                               goto fail;
-                       }
-               } else {
-                       err = f2fs_submit_page_bio(sbi, page, dn.data_blkaddr,
-                                                       READ_SYNC);
-                       if (err)
-                               goto fail;
-               }
+               err = f2fs_submit_page_bio(sbi, page, dn.data_blkaddr,
+                                          READ_SYNC);
+               if (err)
+                       goto fail;
 
                lock_page(page);
                if (unlikely(!PageUptodate(page))) {