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

[Diana Craciun OSS]

Acked-by: Diana Craciun 

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 
---
  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);
  

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

[Alex Williamson]

Hi Diana, same for this one.  Thanks,

Alex

On Fri, 23 Oct 2020 14:29:47 +0300
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 
> ---
>  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);
>  

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

[Dan Carpenter]

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 
---
 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