Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.10 17/24] ubifs: Fix O_TMPFILE corner case in ubifs_link() | Date | Tue, 25 Apr 2017 16:09:26 +0100 |
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4.10-stable review patch. If anyone has any objections, please let me know.
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From: Richard Weinberger <richard@nod.at>
commit 32fe905c17f001c0eee13c59afddd0bf2eed509c upstream.
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: 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- fs/ubifs/dir.c | 7 +++++++ 1 file changed, 7 insertions(+)
--- a/fs/ubifs/dir.c +++ b/fs/ubifs/dir.c @@ -748,6 +748,11 @@ static int ubifs_link(struct dentry *old 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);
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