From 32fe905c17f001c0eee13c59afddd0bf2eed509c Mon Sep 17 00:00:00 2001 From: Richard Weinberger Date: Thu, 30 Mar 2017 10:50:49 +0200 Subject: [PATCH] ubifs: Fix O_TMPFILE corner case in ubifs_link() It is perfectly fine to link a tmpfile back using linkat(). Since tmpfiles are created with a link count of 0 they appear on the orphan list, upon re-linking the inode has to be removed from the orphan list again. Ralph faced a filesystem corruption in combination with overlayfs due to this bug. Cc: Cc: Ralph Sennhauser Cc: Amir Goldstein Reported-by: Ralph Sennhauser Tested-by: Ralph Sennhauser Reported-by: Amir Goldstein Fixes: 474b93704f321 ("ubifs: Implement O_TMPFILE") Signed-off-by: Richard Weinberger --- fs/ubifs/dir.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c index 0858213a4e63..b777bddaa1dd 100644 --- a/fs/ubifs/dir.c +++ b/fs/ubifs/dir.c @@ -748,6 +748,11 @@ static int ubifs_link(struct dentry *old_dentry, struct inode *dir, goto out_fname; lock_2_inodes(dir, inode); + + /* Handle O_TMPFILE corner case, it is allowed to link a O_TMPFILE. */ + if (inode->i_nlink == 0) + ubifs_delete_orphan(c, inode->i_ino); + inc_nlink(inode); ihold(inode); inode->i_ctime = ubifs_current_time(inode); @@ -768,6 +773,8 @@ out_cancel: dir->i_size -= sz_change; dir_ui->ui_size = dir->i_size; drop_nlink(inode); + if (inode->i_nlink == 0) + ubifs_add_orphan(c, inode->i_ino); unlock_2_inodes(dir, inode); ubifs_release_budget(c, &req); iput(inode); -- 2.20.1