ovl: fix missing negative dentry check in ovl_rename()
commit a295aef6 upstream. The following reproducer mkdir lower upper work merge touch lower/old touch lower/new mount -t overlay overlay -olowerdir=lower,upperdir=upper,workdir=work merge rm merge/new mv merge/old merge/new & unlink upper/new may result in this race: PROCESS A: rename("merge/old", "merge/new"); overwrite=true,ovl_lower_positive(old)=true, ovl_dentry_is_whiteout(new)=true -> flags |= RENAME_EXCHANGE PROCESS B: unlink("upper/new"); PROCESS A: lookup newdentry in new_upperdir call vfs_rename() with negative newdentry and RENAME_EXCHANGE Fix by adding the missing check for negative newdentry. Signed-off-by:Zheng Liang <zhengliang6@huawei.com> Fixes: e9be9d5e ("overlay filesystem") Cc: <stable@vger.kernel.org> # v3.18 Signed-off-by:
Miklos Szeredi <mszeredi@redhat.com> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by:
Masami Ichikawa(CIP) <masami.ichikawa@cybertrust.co.jp>
parent
c4078a9c
Please register or sign in to comment