From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH net V2] vhost-vsock: fix use after free Date: Fri, 28 Sep 2018 07:37:37 +0800 Message-ID: <588ed28b-7e4b-9dc8-92ce-d75692836c9e@redhat.com> References: <20180927122204.4188-1-jasowang@redhat.com> <20180927123539-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: stefanha@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, sergei.shtylyov@cogentembedded.com To: "Michael S. Tsirkin" Return-path: In-Reply-To: <20180927123539-mutt-send-email-mst@kernel.org> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 2018年09月28日 01:04, Michael S. Tsirkin wrote: > On Thu, Sep 27, 2018 at 08:22:04PM +0800, Jason Wang wrote: >> The access of vsock is not protected by vhost_vsock_lock. This may >> lead to use after free since vhost_vsock_dev_release() may free the >> pointer at the same time. >> >> Fix this by holding the lock during the access. >> >> Reported-by:syzbot+e3e074963495f92a89ed@syzkaller.appspotmail.com >> Fixes: 16320f363ae1 ("vhost-vsock: add pkt cancel capability") >> Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko") >> Cc: Stefan Hajnoczi >> Signed-off-by: Jason Wang > Wow is that really the best we can do? For net/stable, probably yes. > A global lock on a data path > operation? It's already there, and the patch only increase the critical section. > Granted use after free is nasty but Stefan said he sees > a way to fix it using a per socket refcount. He's on vacation > until Oct 4 though ... > Stefan has acked the pacth, so I think it's ok? We can do optimization for -next on top. Thanks