From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guenter Roeck Subject: Re: [net] vhost: Use kzalloc() to allocate vhost_msg_node Date: Tue, 29 May 2018 20:42:06 -0700 Message-ID: <436712fe-c927-5f42-9cd0-f4234c55a9f7__12245.5423501835$1527651627$gmane$org@roeck-us.net> References: <20180427154502.GA22544@la.guarana.org> <20180529221908.GA22742@roeck-us.net> <20180530055704-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180530055704-mutt-send-email-mst@kernel.org> Content-Language: en-US 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 To: "Michael S. Tsirkin" Cc: Kevin Easton , kvm@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org List-Id: virtualization@lists.linuxfoundation.org On 05/29/2018 08:01 PM, Michael S. Tsirkin wrote: > On Tue, May 29, 2018 at 03:19:08PM -0700, Guenter Roeck wrote: >> On Fri, Apr 27, 2018 at 11:45:02AM -0400, Kevin Easton wrote: >>> The struct vhost_msg within struct vhost_msg_node is copied to userspace, >>> so it should be allocated with kzalloc() to ensure all structure padding >>> is zeroed. >>> >>> Signed-off-by: Kevin Easton >>> Reported-by: syzbot+87cfa083e727a224754b@syzkaller.appspotmail.com >> >> Is this patch going anywhere ? >> >> The patch fixes CVE-2018-1118. It would be useful to understand if and when >> this problem is going to be fixed. >> >> Thanks, >> Guenter >>> --- >>> drivers/vhost/vhost.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c >>> index f3bd8e9..1b84dcff 100644 >>> --- a/drivers/vhost/vhost.c >>> +++ b/drivers/vhost/vhost.c >>> @@ -2339,7 +2339,7 @@ EXPORT_SYMBOL_GPL(vhost_disable_notify); >>> /* Create a new message. */ >>> struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type) >>> { >>> - struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL); >>> + struct vhost_msg_node *node = kzalloc(sizeof *node, GFP_KERNEL); >>> if (!node) >>> return NULL; >>> node->vq = vq; > > As I pointed out, we don't need to init the whole structure. The proper > fix is thus (I think) below. > > Could you use your testing infrastructure to confirm this fixes the issue? > Sorry, I don't have the means to test the fix. Guenter > Thanks! > > Signed-off-by: Michael S. Tsirkin > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index f3bd8e941224..58d9aec90afb 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -2342,6 +2342,9 @@ struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type) > struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL); > if (!node) > return NULL; > + > + /* Make sure all padding within the structure is initialized. */ > + memset(&node->msg, 0, sizeof node->msg); > node->vq = vq; > node->msg.type = type; > return node; >