Re: [PATCH v3] drm/amd/pm: And destination bounds checking to struct copy

[Alex Deucher]

Applied.  Thanks!

Alex

On Thu, Aug 26, 2021 at 11:16 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>
> In preparation for FORTIFY_SOURCE performing compile-time and run-time
> field bounds checking for memcpy(), memmove(), and memset(), avoid
> intentionally writing across neighboring fields.
>
> The "Board Parameters" members of the structs:
>         struct atom_smc_dpm_info_v4_5
>         struct atom_smc_dpm_info_v4_6
>         struct atom_smc_dpm_info_v4_7
>         struct atom_smc_dpm_info_v4_10
> are written to the corresponding members of the corresponding PPTable_t
> variables, but they lack destination size bounds checking, which means
> the compiler cannot verify at compile time that this is an intended and
> safe memcpy().
>
> Since the header files are effectively immutable[1] and a struct_group()
> cannot be used, nor a common struct referenced by both sides of the
> memcpy() arguments, add a new helper, amdgpu_memcpy_trailing(), to
> perform the bounds checking at compile time. Replace the open-coded
> memcpy()s with amdgpu_memcpy_trailing() which includes enough context
> for the bounds checking.
>
> "objdump -d" shows no object code changes.
>
> [1] https://lore.kernel.org/lkml/e56aad3c-a06f-da07-f491-a894a570d78f@xxxxxxx
>
> Cc: "Christian König" <christian.koenig@xxxxxxx>
> Cc: "Pan, Xinhui" <Xinhui.Pan@xxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxx>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> Cc: Hawking Zhang <Hawking.Zhang@xxxxxxx>
> Cc: Feifei Xu <Feifei.Xu@xxxxxxx>
> Cc: Likun Gao <Likun.Gao@xxxxxxx>
> Cc: Jiawei Gu <Jiawei.Gu@xxxxxxx>
> Cc: Evan Quan <evan.quan@xxxxxxx>
> Cc: amd-gfx@xxxxxxxxxxxxxxxxxxxxx
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Reviewed-by: Lijo Lazar <lijo.lazar@xxxxxxx>
> Acked-by: Alex Deucher <alexander.deucher@xxxxxxx>
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
> v3: rename amdgpu_memcpy_trailing() to smu_memcpy_trailing()
> v2: https://lore.kernel.org/lkml/20210825161957.3904130-1-keescook@xxxxxxxxxxxx
> v1: https://lore.kernel.org/lkml/20210819201441.3545027-1-keescook@xxxxxxxxxxxx
> ---
>  drivers/gpu/drm/amd/pm/inc/amdgpu_smu.h       | 24 +++++++++++++++++++
>  .../gpu/drm/amd/pm/swsmu/smu11/arcturus_ppt.c |  6 ++---
>  .../gpu/drm/amd/pm/swsmu/smu11/navi10_ppt.c   |  8 +++----
>  .../drm/amd/pm/swsmu/smu13/aldebaran_ppt.c    |  5 ++--
>  4 files changed, 32 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/pm/inc/amdgpu_smu.h b/drivers/gpu/drm/amd/pm/inc/amdgpu_smu.h
> index 715b4225f5ee..8156729c370b 100644
> --- a/drivers/gpu/drm/amd/pm/inc/amdgpu_smu.h
> +++ b/drivers/gpu/drm/amd/pm/inc/amdgpu_smu.h
> @@ -1335,6 +1335,30 @@ enum smu_cmn2asic_mapping_type {
>  #define WORKLOAD_MAP(profile, workload) \
>         [profile] = {1, (workload)}
>
> +/**
> + * smu_memcpy_trailing - Copy the end of one structure into the middle of another
> + *
> + * @dst: Pointer to destination struct
> + * @first_dst_member: The member name in @dst where the overwrite begins
> + * @last_dst_member: The member name in @dst where the overwrite ends after
> + * @src: Pointer to the source struct
> + * @first_src_member: The member name in @src where the copy begins
> + *
> + */
> +#define smu_memcpy_trailing(dst, first_dst_member, last_dst_member,       \
> +                           src, first_src_member)                         \
> +({                                                                        \
> +       size_t __src_offset = offsetof(typeof(*(src)), first_src_member);  \
> +       size_t __src_size = sizeof(*(src)) - __src_offset;                 \
> +       size_t __dst_offset = offsetof(typeof(*(dst)), first_dst_member);  \
> +       size_t __dst_size = offsetofend(typeof(*(dst)), last_dst_member) - \
> +                           __dst_offset;                                  \
> +       BUILD_BUG_ON(__src_size != __dst_size);                            \
> +       __builtin_memcpy((u8 *)(dst) + __dst_offset,                       \
> +                        (u8 *)(src) + __src_offset,                       \
> +                        __dst_size);                                      \
> +})
> +
>  #if !defined(SWSMU_CODE_LAYER_L2) && !defined(SWSMU_CODE_LAYER_L3) && !defined(SWSMU_CODE_LAYER_L4)
>  int smu_get_power_limit(void *handle,
>                         uint32_t *limit,
> diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu11/arcturus_ppt.c b/drivers/gpu/drm/amd/pm/swsmu/smu11/arcturus_ppt.c
> index 273df66cac14..e343cc218990 100644
> --- a/drivers/gpu/drm/amd/pm/swsmu/smu11/arcturus_ppt.c
> +++ b/drivers/gpu/drm/amd/pm/swsmu/smu11/arcturus_ppt.c
> @@ -483,10 +483,8 @@ static int arcturus_append_powerplay_table(struct smu_context *smu)
>
>         if ((smc_dpm_table->table_header.format_revision == 4) &&
>             (smc_dpm_table->table_header.content_revision == 6))
> -               memcpy(&smc_pptable->MaxVoltageStepGfx,
> -                      &smc_dpm_table->maxvoltagestepgfx,
> -                      sizeof(*smc_dpm_table) - offsetof(struct atom_smc_dpm_info_v4_6, maxvoltagestepgfx));
> -
> +               smu_memcpy_trailing(smc_pptable, MaxVoltageStepGfx, BoardReserved,
> +                                   smc_dpm_table, maxvoltagestepgfx);
>         return 0;
>  }
>
> diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu11/navi10_ppt.c b/drivers/gpu/drm/amd/pm/swsmu/smu11/navi10_ppt.c
> index f96681700c41..a5fc5d7cb6c7 100644
> --- a/drivers/gpu/drm/amd/pm/swsmu/smu11/navi10_ppt.c
> +++ b/drivers/gpu/drm/amd/pm/swsmu/smu11/navi10_ppt.c
> @@ -431,16 +431,16 @@ static int navi10_append_powerplay_table(struct smu_context *smu)
>
>         switch (smc_dpm_table->table_header.content_revision) {
>         case 5: /* nv10 and nv14 */
> -               memcpy(smc_pptable->I2cControllers, smc_dpm_table->I2cControllers,
> -                       sizeof(*smc_dpm_table) - sizeof(smc_dpm_table->table_header));
> +               smu_memcpy_trailing(smc_pptable, I2cControllers, BoardReserved,
> +                                   smc_dpm_table, I2cControllers);
>                 break;
>         case 7: /* nv12 */
>                 ret = amdgpu_atombios_get_data_table(adev, index, NULL, NULL, NULL,
>                                               (uint8_t **)&smc_dpm_table_v4_7);
>                 if (ret)
>                         return ret;
> -               memcpy(smc_pptable->I2cControllers, smc_dpm_table_v4_7->I2cControllers,
> -                       sizeof(*smc_dpm_table_v4_7) - sizeof(smc_dpm_table_v4_7->table_header));
> +               smu_memcpy_trailing(smc_pptable, I2cControllers, BoardReserved,
> +                                   smc_dpm_table_v4_7, I2cControllers);
>                 break;
>         default:
>                 dev_err(smu->adev->dev, "smc_dpm_info with unsupported content revision %d!\n",
> diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu13/aldebaran_ppt.c b/drivers/gpu/drm/amd/pm/swsmu/smu13/aldebaran_ppt.c
> index ec8c30daf31c..ab652028e003 100644
> --- a/drivers/gpu/drm/amd/pm/swsmu/smu13/aldebaran_ppt.c
> +++ b/drivers/gpu/drm/amd/pm/swsmu/smu13/aldebaran_ppt.c
> @@ -409,9 +409,8 @@ static int aldebaran_append_powerplay_table(struct smu_context *smu)
>
>         if ((smc_dpm_table->table_header.format_revision == 4) &&
>             (smc_dpm_table->table_header.content_revision == 10))
> -               memcpy(&smc_pptable->GfxMaxCurrent,
> -                      &smc_dpm_table->GfxMaxCurrent,
> -                      sizeof(*smc_dpm_table) - offsetof(struct atom_smc_dpm_info_v4_10, GfxMaxCurrent));
> +               smu_memcpy_trailing(smc_pptable, GfxMaxCurrent, reserved,
> +                                   smc_dpm_table, GfxMaxCurrent);
>         return 0;
>  }
>
> --
> 2.30.2
>