From: Al Viro <viro@ZenIV.linux.org.uk>
To: Dan Carpenter <error27@gmail.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
Juan Quintela <quintela@redhat.com>,
"David S. Miller" <davem@davemloft.net>,
Rusty Russell <rusty@rustcorp.com.au>,
kvm@vger.kernel.org, virtualization@lists.osdl.org,
netdev@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [patch 1/2] vhost: potential integer overflows
Date: Mon, 11 Oct 2010 18:26:39 +0100 [thread overview]
Message-ID: <20101011172639.GL19804@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20101011172256.GF5851@bicker>
On Mon, Oct 11, 2010 at 07:22:57PM +0200, Dan Carpenter wrote:
> I did an audit for potential integer overflows of values which get passed
> to access_ok() and here are the results.
FWIW, UINT_MAX is wrong here. What you want is maximal size_t value.
> Signed-off-by: Dan Carpenter <error27@gmail.com>
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index dd3d6f7..c2aa12c 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -429,6 +429,14 @@ static int vq_access_ok(unsigned int num,
> struct vring_avail __user *avail,
> struct vring_used __user *used)
> {
> +
> + if (num > UINT_MAX / sizeof *desc)
> + return 0;
> + if (num > UINT_MAX / sizeof *avail->ring - sizeof *avail)
> + return 0;
> + if (num > UINT_MAX / sizeof *used->ring - sizeof *used)
> + return 0;
> +
> return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
> access_ok(VERIFY_READ, avail,
> sizeof *avail + num * sizeof *avail->ring) &&
> @@ -447,6 +455,9 @@ int vhost_log_access_ok(struct vhost_dev *dev)
> /* Caller should have vq mutex and device mutex */
> static int vq_log_access_ok(struct vhost_virtqueue *vq, void __user *log_base)
> {
> + if (vq->num > UINT_MAX / sizeof *vq->used->ring - sizeof *vq->used)
> + return 0;
> +
> return vq_memory_access_ok(log_base, vq->dev->memory,
> vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) &&
> (!vq->log_used || log_access_ok(log_base, vq->log_addr,
> @@ -606,12 +617,17 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
> }
>
> /* Also validate log access for used ring if enabled. */
> - if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
> - !log_access_ok(vq->log_base, a.log_guest_addr,
> + if (a.flags & (0x1 << VHOST_VRING_F_LOG)) {
> + if (vq->num > UINT_MAX / sizeof *vq->used->ring - sizeof *vq->used) {
> + r = -EINVAL;
> + break;
> + }
> + if (!log_access_ok(vq->log_base, a.log_guest_addr,
> sizeof *vq->used +
> vq->num * sizeof *vq->used->ring)) {
> - r = -EINVAL;
> - break;
> + r = -EINVAL;
> + break;
> + }
> }
> }
>
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
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> More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2010-10-11 17:26 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-11 17:22 [patch 1/2] vhost: potential integer overflows Dan Carpenter
2010-10-11 17:26 ` Al Viro [this message]
2010-10-12 12:25 ` Michael S. Tsirkin
2010-10-12 14:51 ` Dan Carpenter
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