| From b50282f3241acee880514212d88b6049fb5039c8 Mon Sep 17 00:00:00 2001 |
| From: Theodore Ts'o <tytso@mit.edu> |
| Date: Mon, 27 Aug 2018 01:47:09 -0400 |
| Subject: ext4: check to make sure the rename(2)'s destination is not freed |
| |
| From: Theodore Ts'o <tytso@mit.edu> |
| |
| commit b50282f3241acee880514212d88b6049fb5039c8 upstream. |
| |
| If the destination of the rename(2) system call exists, the inode's |
| link count (i_nlinks) must be non-zero. If it is, the inode can end |
| up on the orphan list prematurely, leading to all sorts of hilarity, |
| including a use-after-free. |
| |
| https://bugzilla.kernel.org/show_bug.cgi?id=200931 |
| |
| Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
| Reported-by: Wen Xu <wen.xu@gatech.edu> |
| Cc: stable@vger.kernel.org |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| fs/ext4/namei.c | 6 ++++++ |
| 1 file changed, 6 insertions(+) |
| |
| --- a/fs/ext4/namei.c |
| +++ b/fs/ext4/namei.c |
| @@ -3514,6 +3514,12 @@ static int ext4_rename(struct inode *old |
| int credits; |
| u8 old_file_type; |
| |
| + if (new.inode && new.inode->i_nlink == 0) { |
| + EXT4_ERROR_INODE(new.inode, |
| + "target of rename is already freed"); |
| + return -EFSCORRUPTED; |
| + } |
| + |
| if ((ext4_test_inode_flag(new_dir, EXT4_INODE_PROJINHERIT)) && |
| (!projid_eq(EXT4_I(new_dir)->i_projid, |
| EXT4_I(old_dentry->d_inode)->i_projid))) |
