From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH net] vhost: Use kzalloc() to allocate vhost_msg_node Date: Mon, 7 May 2018 16:03:25 +0300 Message-ID: <20180507155534-mutt-send-email-mst@kernel.org> References: <000000000000a5b2b1056a86e98c@google.com> <20180427154502.GA22544@la.guarana.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jason Wang , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com To: Kevin Easton Return-path: Content-Disposition: inline In-Reply-To: <20180427154502.GA22544@la.guarana.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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 > --- > 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; Let's just init the msg though. OK it seems this is the best we can do for now, we need a new feature bit to fix it for 32 bit userspace on 64 bit kernels. Does the following help? Signed-off-by: Michael S. Tsirkin diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index f3bd8e9..58d9aec 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;