Re: [PATCH 2/2] vfio/fsl-mc: prevent underflow in vfio_fsl_mc_mmap()
From: Diana Craciun OSS
Date: Tue Nov 03 2020 - 07:03:23 EST
Acked-by: Diana Craciun <diana.craciun@xxxxxxxxxxx>
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 <dan.carpenter@xxxxxxxxxx>
---
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);