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SubjectRe: [PATCH] fpga: dfl-afu-region: Add overflow checks for region size and offset
On 2023-02-05 at 21:43:26 -0800, k1rh4.lee@gmail.com wrote:
> From: Sangsup Lee <k1rh4.lee@gmail.com>
>
> The size + offset is able to be integer overflow value and it lead to mis-allocate region.

But I didn't see the memory allocation.

>
> Signed-off-by: Sangsup Lee <k1rh4.lee@gmail.com>
> ---
> drivers/fpga/dfl-afu-region.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/fpga/dfl-afu-region.c b/drivers/fpga/dfl-afu-region.c
> index 2e7b41629406..82b530111601 100644
> --- a/drivers/fpga/dfl-afu-region.c
> +++ b/drivers/fpga/dfl-afu-region.c
> @@ -151,12 +151,17 @@ int afu_mmio_region_get_by_offset(struct dfl_feature_platform_data *pdata,
> struct dfl_afu_mmio_region *region;
> struct dfl_afu *afu;
> int ret = 0;
> + u64 region_size = 0;

Reverse Xmax tree please.

>
> mutex_lock(&pdata->lock);
> + if (check_add_overflow(offset, size, &region_size)) {

I'm not sure if the check is necessary.

The offset comes from: offset = vma->vm_pgoff << PAGE_SHIFT
The size comes from: size = vma->vm_end - vma->vm_start
Is it possible the upper mm layer passes invalid vma?

Thanks,
Yilun

> + ret = -EINVAL;
> + goto exit;
> + }
> afu = dfl_fpga_pdata_get_private(pdata);
> for_each_region(region, afu)
> if (region->offset <= offset &&
> - region->offset + region->size >= offset + size) {
> + region->offset + region->size >= region_size) {
> *pregion = *region;
> goto exit;
> }
> --
> 2.25.1
>

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