[PATCH] drm/amdgpu: detect buffer overflow and avoid unnecessary dereference

[Alex Deucher]

On Tue, May 29, 2018 at 6:17 AM, Evan Quan <evan.quan at amd.com> wrote:
> Change-Id: I6666d7dcf60acf524f290460d2ffe3f1f5f46354
> Signed-off-by: Evan Quan <evan.quan at amd.com>

Please include a patch description as well.  One comment below.

> ---
>  drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> index 7c5a850..5a86726 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> @@ -1838,13 +1838,15 @@ static void gfx_v9_1_parse_ind_reg_list(int *register_list_format,
>                                 int indirect_offset,
>                                 int list_size,
>                                 int *unique_indirect_regs,
> -                               int *unique_indirect_reg_count,
> +                               int unique_indirect_reg_count,
>                                 int *indirect_start_offsets,
> -                               int *indirect_start_offsets_count)
> +                               int *indirect_start_offsets_count,
> +                               int max_start_offsets_count)
>  {
>         int idx;
>
>         for (; indirect_offset < list_size; indirect_offset++) {
> +               BUG_ON(*indirect_start_offsets_count >= max_start_offsets_count);

Maybe this should be a WARN_ON and then we clamp the range?

Alex

>                 indirect_start_offsets[*indirect_start_offsets_count] = indirect_offset;
>                 *indirect_start_offsets_count = *indirect_start_offsets_count + 1;
>
> @@ -1852,14 +1854,14 @@ static void gfx_v9_1_parse_ind_reg_list(int *register_list_format,
>                         indirect_offset += 2;
>
>                         /* look for the matching indice */
> -                       for (idx = 0; idx < *unique_indirect_reg_count; idx++) {
> +                       for (idx = 0; idx < unique_indirect_reg_count; idx++) {
>                                 if (unique_indirect_regs[idx] ==
>                                         register_list_format[indirect_offset] ||
>                                         !unique_indirect_regs[idx])
>                                         break;
>                         }
>
> -                       BUG_ON(idx >= *unique_indirect_reg_count);
> +                       BUG_ON(idx >= unique_indirect_reg_count);
>
>                         if (!unique_indirect_regs[idx])
>                                 unique_indirect_regs[idx] = register_list_format[indirect_offset];
> @@ -1894,9 +1896,10 @@ static int gfx_v9_1_init_rlc_save_restore_list(struct amdgpu_device *adev)
>                                     adev->gfx.rlc.reg_list_format_direct_reg_list_length,
>                                     adev->gfx.rlc.reg_list_format_size_bytes >> 2,
>                                     unique_indirect_regs,
> -                                   &unique_indirect_reg_count,
> +                                   unique_indirect_reg_count,
>                                     indirect_start_offsets,
> -                                   &indirect_start_offsets_count);
> +                                   &indirect_start_offsets_count,
> +                                   ARRAY_SIZE(indirect_start_offsets));
>
>         /* enable auto inc in case it is disabled */
>         tmp = RREG32(SOC15_REG_OFFSET(GC, 0, mmRLC_SRM_CNTL));
> --
> 2.7.4
>
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