From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PULL] vhost: cleanups and fixes Date: Fri, 30 Nov 2018 08:44:16 -0500 Message-ID: <20181130084227-mutt-send-email-mst@kernel.org> References: <20181101171938-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: lenaic@lhuard.fr, mhocko@suse.com, Kees Cook , kvm@vger.kernel.org, netdev@vger.kernel.org, liang.z.li@intel.com, Linux Kernel Mailing List , virtualization@lists.linux-foundation.org, stefanha@redhat.com, joe@perches.com, Andrew Morton , mhocko@kernel.org, bijan.mottahedeh@oracle.com To: Linus Torvalds Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: kvm.vger.kernel.org On Thu, Nov 01, 2018 at 04:06:19PM -0700, Linus Torvalds wrote: > On Thu, Nov 1, 2018 at 4:00 PM Kees Cook wrote: > > > > + memset(&rsp, 0, sizeof(rsp)); > > + rsp.response = VIRTIO_SCSI_S_FUNCTION_REJECTED; > > + resp = vq->iov[out].iov_base; > > + ret = __copy_to_user(resp, &rsp, sizeof(rsp)); > > > > Is it actually safe to trust that iov_base has passed an earlier > > access_ok() check here? Why not just use copy_to_user() instead? > > Good point. > > We really should have removed those double-underscore things ages ago. > > Also, apart from the address, what about the size? Wouldn't it be > better to use copy_to_iter() rather than implement it badly by hand? > > Linus Bijan can you respond please? Are you going to look into this and convert code to copy_to_iter? I don't think we should release Linux like this, so if you don't have the time I'd rather revert for now and you can look into reposting for the next release. Thanks, -- MST