The dev->vqs[] array has "dev->vq_num" elements.  It's allocated in
vduse_dev_init_vqs().  Thus, this > comparison needs to be >= to avoid
reading one element beyond the end of the array.

Add an array_index_nospec() as well to prevent speculation issues.

Fixes: 316ecd1346b0 ("vduse: Add file operation for mmap")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
v2: add array_index_nospec().

 drivers/vdpa/vdpa_user/vduse_dev.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index b7a1fb88c506..eb914084c650 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -1532,9 +1532,10 @@ static int vduse_dev_mmap(struct file *file, struct vm_area_struct *vma)
 	if ((vma->vm_flags & VM_SHARED) == 0)
 		return -EINVAL;
 
-	if (index > dev->vq_num)
+	if (index >= dev->vq_num)
 		return -EINVAL;

 	vq = dev->vqs[index];
 	vaddr = vq->vdpa_reconnect_vaddr;
 	if (vaddr == 0)
-- 
2.43.0

On Wed, 28 Feb 2024 at 12:44, Dan Carpenter <dan.carpenter@linaro.org> wrote:
>
> The dev->vqs[] array has "dev->vq_num" elements.  It's allocated in
> vduse_dev_init_vqs().  Thus, this > comparison needs to be >= to avoid
> reading one element beyond the end of the array.
>
> Add an array_index_nospec() as well to prevent speculation issues.
>
> Fixes: 316ecd1346b0 ("vduse: Add file operation for mmap")
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> ---
> v2: add array_index_nospec().

Did you forget to update the patch, I don't see array_index_nospec()?

>
>  drivers/vdpa/vdpa_user/vduse_dev.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index b7a1fb88c506..eb914084c650 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -1532,9 +1532,10 @@ static int vduse_dev_mmap(struct file *file, struct vm_area_struct *vma)
>         if ((vma->vm_flags & VM_SHARED) == 0)
>                 return -EINVAL;
>
> -       if (index > dev->vq_num)
> +       if (index >= dev->vq_num)
>                 return -EINVAL;
>
>         vq = dev->vqs[index];
>         vaddr = vq->vdpa_reconnect_vaddr;
>         if (vaddr == 0)
> --
> 2.43.0
>
>

On Wed, Feb 28, 2024 at 12:53:28PM -0500, Stefan Hajnoczi wrote:
> On Wed, 28 Feb 2024 at 12:44, Dan Carpenter <dan.carpenter@linaro.org> wrote:
> >
> > The dev->vqs[] array has "dev->vq_num" elements.  It's allocated in
> > vduse_dev_init_vqs().  Thus, this > comparison needs to be >= to avoid
> > reading one element beyond the end of the array.
> >
> > Add an array_index_nospec() as well to prevent speculation issues.
> >
> > Fixes: 316ecd1346b0 ("vduse: Add file operation for mmap")
> > Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> > ---
> > v2: add array_index_nospec().
> 
> Did you forget to update the patch, I don't see array_index_nospec()?
> 
> >
> >  drivers/vdpa/vdpa_user/vduse_dev.c | 3 ++-
                                          ^^^^^
I updated the patch but the thing about vim is that every time you
press a button it does something unexpected.  Vim ate my homework.

regards,
dan carpenter