exfat: use updated exfat_chain directly during renaming

commit 204e6ceaa1035cb7b92b156517e88842ebb4c7ff upstream.

In order for a file to access its own directory entry set,
exfat_inode_info(ei) has two copied values. One is ei->dir, which is
a snapshot of exfat_chain of the parent directory, and the other is
ei->entry, which is the offset of the start of the directory entry set
in the parent directory.

Since the parent directory can be updated after the snapshot point,
it should be used only for accessing one's own directory entry set.

However, as of now, during renaming, it could try to traverse or to
allocate clusters via snapshot values, it does not make sense.

This potential problem has been revealed when exfat_update_parent_info()
was removed by commit d8dad2588add ("exfat: fix referencing wrong parent
directory information after renaming"). However, I don't think it's good
idea to bring exfat_update_parent_info() back.

Instead, let's use the updated exfat_chain of parent directory diectly.

Fixes: d8dad2588add ("exfat: fix referencing wrong parent directory information after renaming")
Reported-by: Wang Yugui <wangyugui@e16-tech.com>
Signed-off-by: Sungjong Seo <sj1557.seo@samsung.com>
Tested-by: Wang Yugui <wangyugui@e16-tech.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c
index 939737ba520d0119bb411e821fe8a85fbfb9b3f9..8a7f4c0830f3d7b05906229c1926d4d653f4fac4 100644 (file)
--- a/fs/exfat/namei.c
+++ b/fs/exfat/namei.c
@@ -1190,7 +1190,9 @@ static int __exfat_rename(struct inode *old_parent_inode,
                return -ENOENT;
        }
 
-       exfat_chain_dup(&olddir, &ei->dir);
+       exfat_chain_set(&olddir, EXFAT_I(old_parent_inode)->start_clu,
+               EXFAT_B_TO_CLU_ROUND_UP(i_size_read(old_parent_inode), sbi),
+               EXFAT_I(old_parent_inode)->flags);
        dentry = ei->entry;
 
        ep = exfat_get_dentry(sb, &olddir, dentry, &old_bh, NULL);