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Date: Tue, 10 Apr 2018 16:29:13 +0300
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Stefan Hajnoczi <stefanha@...hat.com>
Cc: virtualization@...ts.linux-foundation.org,
syzkaller-bugs@...glegroups.com,
Linus Torvalds <torvalds@...ux-foundation.org>,
kvm@...r.kernel.org, jasowang@...hat.com,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH v2 2/2] vhost: return bool from *_access_ok() functions
On Tue, Apr 10, 2018 at 01:26:30PM +0800, Stefan Hajnoczi wrote:
> Currently vhost *_access_ok() functions return int. This is error-prone
> because there are two popular conventions:
>
> 1. 0 means failure, 1 means success
> 2. -errno means failure, 0 means success
>
> Although vhost mostly uses #1, it does not do so consistently.
> umem_access_ok() uses #2.
>
> This patch changes the return type from int to bool so that false means
> failure and true means success. This eliminates a potential source of
> errors.
>
> Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
> Signed-off-by: Stefan Hajnoczi <stefanha@...hat.com>
Acked-by: Michael S. Tsirkin <mst@...hat.com>
> ---
> drivers/vhost/vhost.h | 4 ++--
> drivers/vhost/vhost.c | 66 +++++++++++++++++++++++++--------------------------
> 2 files changed, 35 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
> index ac4b6056f19a..6e00fa57af09 100644
> --- a/drivers/vhost/vhost.h
> +++ b/drivers/vhost/vhost.h
> @@ -178,8 +178,8 @@ void vhost_dev_cleanup(struct vhost_dev *);
> void vhost_dev_stop(struct vhost_dev *);
> long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, void __user *argp);
> long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp);
> -int vhost_vq_access_ok(struct vhost_virtqueue *vq);
> -int vhost_log_access_ok(struct vhost_dev *);
> +bool vhost_vq_access_ok(struct vhost_virtqueue *vq);
> +bool vhost_log_access_ok(struct vhost_dev *);
>
> int vhost_get_vq_desc(struct vhost_virtqueue *,
> struct iovec iov[], unsigned int iov_count,
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 93fd0c75b0d8..b6a082ef33dd 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -641,14 +641,14 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
> }
> EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
>
> -static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
> +static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
> {
> u64 a = addr / VHOST_PAGE_SIZE / 8;
>
> /* Make sure 64 bit math will not overflow. */
> if (a > ULONG_MAX - (unsigned long)log_base ||
> a + (unsigned long)log_base > ULONG_MAX)
> - return 0;
> + return false;
>
> return access_ok(VERIFY_WRITE, log_base + a,
> (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
> @@ -661,30 +661,30 @@ static bool vhost_overflow(u64 uaddr, u64 size)
> }
>
> /* Caller should have vq mutex and device mutex. */
> -static int vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
> - int log_all)
> +static bool vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
> + int log_all)
> {
> struct vhost_umem_node *node;
>
> if (!umem)
> - return 0;
> + return false;
>
> list_for_each_entry(node, &umem->umem_list, link) {
> unsigned long a = node->userspace_addr;
>
> if (vhost_overflow(node->userspace_addr, node->size))
> - return 0;
> + return false;
>
>
> if (!access_ok(VERIFY_WRITE, (void __user *)a,
> node->size))
> - return 0;
> + return false;
> else if (log_all && !log_access_ok(log_base,
> node->start,
> node->size))
> - return 0;
> + return false;
> }
> - return 1;
> + return true;
> }
>
> static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
> @@ -701,13 +701,13 @@ static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
>
> /* Can we switch to this memory table? */
> /* Caller should have device mutex but not vq mutex */
> -static int memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
> - int log_all)
> +static bool memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
> + int log_all)
> {
> int i;
>
> for (i = 0; i < d->nvqs; ++i) {
> - int ok;
> + bool ok;
> bool log;
>
> mutex_lock(&d->vqs[i]->mutex);
> @@ -717,12 +717,12 @@ static int memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
> ok = vq_memory_access_ok(d->vqs[i]->log_base,
> umem, log);
> else
> - ok = 1;
> + ok = true;
> mutex_unlock(&d->vqs[i]->mutex);
> if (!ok)
> - return 0;
> + return false;
> }
> - return 1;
> + return true;
> }
>
> static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
> @@ -959,21 +959,21 @@ static void vhost_iotlb_notify_vq(struct vhost_dev *d,
> spin_unlock(&d->iotlb_lock);
> }
>
> -static int umem_access_ok(u64 uaddr, u64 size, int access)
> +static bool umem_access_ok(u64 uaddr, u64 size, int access)
> {
> unsigned long a = uaddr;
>
> /* Make sure 64 bit math will not overflow. */
> if (vhost_overflow(uaddr, size))
> - return -EFAULT;
> + return false;
>
> if ((access & VHOST_ACCESS_RO) &&
> !access_ok(VERIFY_READ, (void __user *)a, size))
> - return -EFAULT;
> + return false;
> if ((access & VHOST_ACCESS_WO) &&
> !access_ok(VERIFY_WRITE, (void __user *)a, size))
> - return -EFAULT;
> - return 0;
> + return false;
> + return true;
> }
>
> static int vhost_process_iotlb_msg(struct vhost_dev *dev,
> @@ -988,7 +988,7 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev,
> ret = -EFAULT;
> break;
> }
> - if (umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
> + if (!umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
> ret = -EFAULT;
> break;
> }
> @@ -1135,10 +1135,10 @@ static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
> return 0;
> }
>
> -static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
> - struct vring_desc __user *desc,
> - struct vring_avail __user *avail,
> - struct vring_used __user *used)
> +static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
> + struct vring_desc __user *desc,
> + struct vring_avail __user *avail,
> + struct vring_used __user *used)
>
> {
> size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
> @@ -1161,8 +1161,8 @@ static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
> vq->meta_iotlb[type] = node;
> }
>
> -static int iotlb_access_ok(struct vhost_virtqueue *vq,
> - int access, u64 addr, u64 len, int type)
> +static bool iotlb_access_ok(struct vhost_virtqueue *vq,
> + int access, u64 addr, u64 len, int type)
> {
> const struct vhost_umem_node *node;
> struct vhost_umem *umem = vq->iotlb;
> @@ -1220,7 +1220,7 @@ EXPORT_SYMBOL_GPL(vq_iotlb_prefetch);
>
> /* Can we log writes? */
> /* Caller should have device mutex but not vq mutex */
> -int vhost_log_access_ok(struct vhost_dev *dev)
> +bool vhost_log_access_ok(struct vhost_dev *dev)
> {
> return memory_access_ok(dev, dev->umem, 1);
> }
> @@ -1228,8 +1228,8 @@ EXPORT_SYMBOL_GPL(vhost_log_access_ok);
>
> /* Verify access for write logging. */
> /* Caller should have vq mutex and device mutex */
> -static int vq_log_access_ok(struct vhost_virtqueue *vq,
> - void __user *log_base)
> +static bool vq_log_access_ok(struct vhost_virtqueue *vq,
> + void __user *log_base)
> {
> size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
>
> @@ -1242,14 +1242,14 @@ static int vq_log_access_ok(struct vhost_virtqueue *vq,
>
> /* Can we start vq? */
> /* Caller should have vq mutex and device mutex */
> -int vhost_vq_access_ok(struct vhost_virtqueue *vq)
> +bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
> {
> if (!vq_log_access_ok(vq, vq->log_base))
> - return 0;
> + return false;
>
> /* Access validation occurs at prefetch time with IOTLB */
> if (vq->iotlb)
> - return 1;
> + return true;
>
> return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
> }
> --
> 2.14.3
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