2020-10-23 17:51:18

by Dan Carpenter

Subject: [PATCH 2/2] vfio/fsl-mc: prevent underflow in vfio_fsl_mc_mmap()

My static analsysis tool complains that the "index" can be negative.
There are some checks in do_mmap() which try to prevent underflows but
I don't know if they are sufficient for this situation. Either way,
making "index" unsigned is harmless so let's do it just to be safe.

Fixes: 67247289688d ("vfio/fsl-mc: Allow userspace to MMAP fsl-mc device MMIO regions")
Signed-off-by: Dan Carpenter <[email protected]>
---
drivers/vfio/fsl-mc/vfio_fsl_mc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
index 21f22e3da11f..f27e25112c40 100644
--- a/drivers/vfio/fsl-mc/vfio_fsl_mc.c
+++ b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
@@ -472,7 +472,7 @@ static int vfio_fsl_mc_mmap(void *device_data, struct vm_area_struct *vma)
{
struct vfio_fsl_mc_device *vdev = device_data;
struct fsl_mc_device *mc_dev = vdev->mc_dev;
- int index;
+ unsigned int index;

index = vma->vm_pgoff >> (VFIO_FSL_MC_OFFSET_SHIFT - PAGE_SHIFT);

--
2.28.0

2020-11-02 21:48:19

by Alex Williamson

Subject: Re: [PATCH 2/2] vfio/fsl-mc: prevent underflow in vfio_fsl_mc_mmap()

Hi Diana, same for this one. Thanks,

Alex

On Fri, 23 Oct 2020 14:29:47 +0300
Dan Carpenter <[email protected]> wrote:

> My static analsysis tool complains that the "index" can be negative.
> There are some checks in do_mmap() which try to prevent underflows but
> I don't know if they are sufficient for this situation. Either way,
> making "index" unsigned is harmless so let's do it just to be safe.
>
> Fixes: 67247289688d ("vfio/fsl-mc: Allow userspace to MMAP fsl-mc device MMIO regions")
> Signed-off-by: Dan Carpenter <[email protected]>
> ---
> drivers/vfio/fsl-mc/vfio_fsl_mc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> index 21f22e3da11f..f27e25112c40 100644
> --- a/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> @@ -472,7 +472,7 @@ static int vfio_fsl_mc_mmap(void *device_data, struct vm_area_struct *vma)
> {
> struct vfio_fsl_mc_device *vdev = device_data;
> struct fsl_mc_device *mc_dev = vdev->mc_dev;
> - int index;
> + unsigned int index;
>
> index = vma->vm_pgoff >> (VFIO_FSL_MC_OFFSET_SHIFT - PAGE_SHIFT);
>

2020-11-03 12:05:37

by Diana Madalina Craciun

Subject: Re: [PATCH 2/2] vfio/fsl-mc: prevent underflow in vfio_fsl_mc_mmap()

Acked-by: Diana Craciun <[email protected]>

On 10/23/2020 2:29 PM, Dan Carpenter wrote:
> My static analsysis tool complains that the "index" can be negative.
> There are some checks in do_mmap() which try to prevent underflows but
> I don't know if they are sufficient for this situation. Either way,
> making "index" unsigned is harmless so let's do it just to be safe.
>
> Fixes: 67247289688d ("vfio/fsl-mc: Allow userspace to MMAP fsl-mc device MMIO regions")
> Signed-off-by: Dan Carpenter <[email protected]>
> ---
> drivers/vfio/fsl-mc/vfio_fsl_mc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> index 21f22e3da11f..f27e25112c40 100644
> --- a/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> @@ -472,7 +472,7 @@ static int vfio_fsl_mc_mmap(void *device_data, struct vm_area_struct *vma)
> {
> struct vfio_fsl_mc_device *vdev = device_data;
> struct fsl_mc_device *mc_dev = vdev->mc_dev;
> - int index;
> + unsigned int index;
>
> index = vma->vm_pgoff >> (VFIO_FSL_MC_OFFSET_SHIFT - PAGE_SHIFT);
>
>