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: <stable@vger.kernel.org>
Cc: Ralph Sennhauser <ralph.sennhauser@gmail.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Reported-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>
Tested-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>
Reported-by: Amir Goldstein <amir73il@gmail.com>
Fixes: 474b93704f321 ("ubifs: Implement O_TMPFILE")
Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index 0858213..b777bdd 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -748,6 +748,11 @@
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 @@
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);
