[PATCH 5/5] drm/amdgpu: Fix potential integer overflows

[Alex Deucher]

On Tue, Jul 9, 2019 at 11:59 PM Kuehling, Felix <Felix.Kuehling at amd.com> wrote:
>
> With mm_nodes larger than 4GB, byte_count in amdgpu_fill_buffer would
> overflow.
>
> Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>

Good catch.
Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index ae0eb64e734b..bbbf069efb77 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -2071,9 +2071,9 @@ int amdgpu_fill_buffer(struct amdgpu_bo *bo,
>         mm_node = bo->tbo.mem.mm_node;
>         num_loops = 0;
>         while (num_pages) {
> -               uint32_t byte_count = mm_node->size << PAGE_SHIFT;
> +               uint64_t byte_count = mm_node->size << PAGE_SHIFT;
>
> -               num_loops += DIV_ROUND_UP(byte_count, max_bytes);
> +               num_loops += DIV_ROUND_UP_ULL(byte_count, max_bytes);
>                 num_pages -= mm_node->size;
>                 ++mm_node;
>         }
> @@ -2099,12 +2099,13 @@ int amdgpu_fill_buffer(struct amdgpu_bo *bo,
>         mm_node = bo->tbo.mem.mm_node;
>
>         while (num_pages) {
> -               uint32_t byte_count = mm_node->size << PAGE_SHIFT;
> +               uint64_t byte_count = mm_node->size << PAGE_SHIFT;
>                 uint64_t dst_addr;
>
>                 dst_addr = amdgpu_mm_node_addr(&bo->tbo, mm_node, &bo->tbo.mem);
>                 while (byte_count) {
> -                       uint32_t cur_size_in_bytes = min(byte_count, max_bytes);
> +                       uint32_t cur_size_in_bytes = min_t(uint64_t, byte_count,
> +                                                          max_bytes);
>
>                         amdgpu_emit_fill_buffer(adev, &job->ibs[0], src_data,
>                                                 dst_addr, cur_size_in_bytes);
> --
> 2.17.1
>
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