fs: ocfs2: fix a possible null-pointer dereference in ocfs2_write_end…

…_nolock()

In ocfs2_write_end_nolock(), there are an if statement on lines 1976,
2047 and 2058, to check whether handle is NULL:

    if (handle)

When handle is NULL, it is used on line 2045:

	ocfs2_update_inode_fsync_trans(handle, inode, 1);
        oi->i_sync_tid = handle->h_transaction->t_tid;

Thus, a possible null-pointer dereference may occur.

To fix this bug, handle is checked before calling
ocfs2_update_inode_fsync_trans().

This bug is found by a static analysis tool STCheck written by us.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Jia-Ju Bai <[email protected]>
Reviewed-by: Joseph Qi <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: Junxiao Bi <[email protected]>
Cc: Changwei Ge <[email protected]>
Cc: Gang He <[email protected]>
Cc: Jun Piao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

fs/ocfs2/aops.c

@@ -2049,7 +2049,8 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
 		inode->i_mtime = inode->i_ctime = current_time(inode);
 		di->i_mtime = di->i_ctime = cpu_to_le64(inode->i_mtime.tv_sec);
 		di->i_mtime_nsec = di->i_ctime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
-		ocfs2_update_inode_fsync_trans(handle, inode, 1);
+		if (handle)
+			ocfs2_update_inode_fsync_trans(handle, inode, 1);
 	}
 	if (handle)
 		ocfs2_journal_dirty(handle, wc->w_di_bh);