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Date: Thu, 27 May 2010 13:48:30 +0300
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Takuya Yoshikawa <yoshikawa.takuya@....ntt.co.jp>
Cc: kvm@...r.kernel.org, virtualization@...ts.osdl.org,
netdev@...r.kernel.org
Subject: Re: [PATCH 1/3] vhost: fix to check the return value of
copy_to/from_user() correctly
On Thu, May 27, 2010 at 06:58:03PM +0900, Takuya Yoshikawa wrote:
> copy_to/from_user() returns the number of bytes that could not be copied.
>
> So we need to check if it is not zero, and in that case, we should return
> the error number -EFAULT rather than directly return the return value from
> copy_to/from_user().
>
> Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@....ntt.co.jp>
Thanks, applied.
> ---
> drivers/vhost/vhost.c | 51 ++++++++++++++++++++++++++----------------------
> 1 files changed, 28 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 5c9c657..9633a3c 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -320,10 +320,8 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
> {
> struct vhost_memory mem, *newmem, *oldmem;
> unsigned long size = offsetof(struct vhost_memory, regions);
> - long r;
> - r = copy_from_user(&mem, m, size);
> - if (r)
> - return r;
> + if (copy_from_user(&mem, m, size))
> + return -EFAULT;
> if (mem.padding)
> return -EOPNOTSUPP;
> if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS)
> @@ -333,11 +331,10 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
> return -ENOMEM;
>
> memcpy(newmem, &mem, size);
> - r = copy_from_user(newmem->regions, m->regions,
> - mem.nregions * sizeof *m->regions);
> - if (r) {
> + if (copy_from_user(newmem->regions, m->regions,
> + mem.nregions * sizeof *m->regions)) {
> kfree(newmem);
> - return r;
> + return -EFAULT;
> }
>
> if (!memory_access_ok(d, newmem, vhost_has_feature(d, VHOST_F_LOG_ALL)))
> @@ -389,9 +386,10 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
> r = -EBUSY;
> break;
> }
> - r = copy_from_user(&s, argp, sizeof s);
> - if (r < 0)
> + if (copy_from_user(&s, argp, sizeof s)) {
> + r = -EFAULT;
> break;
> + }
> if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
> r = -EINVAL;
> break;
> @@ -405,9 +403,10 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
> r = -EBUSY;
> break;
> }
> - r = copy_from_user(&s, argp, sizeof s);
> - if (r < 0)
> + if (copy_from_user(&s, argp, sizeof s)) {
> + r = -EFAULT;
> break;
> + }
> if (s.num > 0xffff) {
> r = -EINVAL;
> break;
> @@ -419,12 +418,14 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
> case VHOST_GET_VRING_BASE:
> s.index = idx;
> s.num = vq->last_avail_idx;
> - r = copy_to_user(argp, &s, sizeof s);
> + if (copy_to_user(argp, &s, sizeof s))
> + r = -EFAULT;
> break;
> case VHOST_SET_VRING_ADDR:
> - r = copy_from_user(&a, argp, sizeof a);
> - if (r < 0)
> + if (copy_from_user(&a, argp, sizeof a)) {
> + r = -EFAULT;
> break;
> + }
> if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
> r = -EOPNOTSUPP;
> break;
> @@ -477,9 +478,10 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
> vq->used = (void __user *)(unsigned long)a.used_user_addr;
> break;
> case VHOST_SET_VRING_KICK:
> - r = copy_from_user(&f, argp, sizeof f);
> - if (r < 0)
> + if (copy_from_user(&f, argp, sizeof f)) {
> + r = -EFAULT;
> break;
> + }
> eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
> if (IS_ERR(eventfp)) {
> r = PTR_ERR(eventfp);
> @@ -492,9 +494,10 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
> filep = eventfp;
> break;
> case VHOST_SET_VRING_CALL:
> - r = copy_from_user(&f, argp, sizeof f);
> - if (r < 0)
> + if (copy_from_user(&f, argp, sizeof f)) {
> + r = -EFAULT;
> break;
> + }
> eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
> if (IS_ERR(eventfp)) {
> r = PTR_ERR(eventfp);
> @@ -510,9 +513,10 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
> filep = eventfp;
> break;
> case VHOST_SET_VRING_ERR:
> - r = copy_from_user(&f, argp, sizeof f);
> - if (r < 0)
> + if (copy_from_user(&f, argp, sizeof f)) {
> + r = -EFAULT;
> break;
> + }
> eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
> if (IS_ERR(eventfp)) {
> r = PTR_ERR(eventfp);
> @@ -575,9 +579,10 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg)
> r = vhost_set_memory(d, argp);
> break;
> case VHOST_SET_LOG_BASE:
> - r = copy_from_user(&p, argp, sizeof p);
> - if (r < 0)
> + if (copy_from_user(&p, argp, sizeof p)) {
> + r = -EFAULT;
> break;
> + }
> if ((u64)(unsigned long)p != p) {
> r = -EFAULT;
> break;
> --
> 1.7.0.4
--
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