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Date:   Thu, 26 Aug 2021 20:09:55 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Alex Deucher <alexdeucher@...il.com>
Cc:     Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Hawking Zhang <Hawking.Zhang@....com>,
        Feifei Xu <Feifei.Xu@....com>, Likun Gao <Likun.Gao@....com>,
        Jiawei Gu <Jiawei.Gu@....com>, Evan Quan <evan.quan@....com>,
        amd-gfx list <amd-gfx@...ts.freedesktop.org>,
        Maling list - DRI developers 
        <dri-devel@...ts.freedesktop.org>, Lijo Lazar <lijo.lazar@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Andrey Grodzovsky <andrey.grodzovsky@....com>,
        Luben Tuikov <luben.tuikov@....com>,
        Sathishkumar S <sathishkumar.sundararaju@....com>,
        Jonathan Kim <jonathan.kim@....com>,
        Darren Powell <darren.powell@....com>,
        Huang Rui <ray.huang@....com>,
        Xiaojian Du <Xiaojian.Du@....com>,
        Ryan Taylor <Ryan.Taylor@....com>,
        Graham Sider <Graham.Sider@....com>,
        Kevin Wang <kevin1.wang@....com>,
        David M Nieto <David.Nieto@....com>,
        Lee Jones <lee.jones@...aro.org>,
        John Clements <john.clements@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2] drm/amd/pm: And destination bounds checking to struct
 copy

On Thu, Aug 26, 2021 at 03:51:29PM -0400, Alex Deucher wrote:
> On Wed, Aug 25, 2021 at 12:20 PM Kees Cook <keescook@...omium.org> 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@amd.com
> >
> > Cc: "Christian König" <christian.koenig@....com>
> > Cc: "Pan, Xinhui" <Xinhui.Pan@....com>
> > Cc: David Airlie <airlied@...ux.ie>
> > Cc: Daniel Vetter <daniel@...ll.ch>
> > Cc: Hawking Zhang <Hawking.Zhang@....com>
> > Cc: Feifei Xu <Feifei.Xu@....com>
> > Cc: Likun Gao <Likun.Gao@....com>
> > Cc: Jiawei Gu <Jiawei.Gu@....com>
> > Cc: Evan Quan <evan.quan@....com>
> > Cc: amd-gfx@...ts.freedesktop.org
> > Cc: dri-devel@...ts.freedesktop.org
> > Reviewed-by: Lijo Lazar <lijo.lazar@....com>
> > Acked-by: Alex Deucher <alexander.deucher@....com>
> > Signed-off-by: Kees Cook <keescook@...omium.org>
> > ---
> > v2:
> > - rename and move helper to drivers/gpu/drm/amd/pm/inc/amdgpu_smu.h
> > - add reviews/acks
> > v1: https://lore.kernel.org/lkml/20210819201441.3545027-1-keescook@chromium.org/
> > ---
> >  drivers/gpu/drm/amd/amdgpu/amdgpu.h           |  1 +
> >  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 ++--
> >  5 files changed, 33 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > index dc3c6b3a00e5..c911387045e2 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > @@ -1452,4 +1452,5 @@ static inline int amdgpu_in_reset(struct amdgpu_device *adev)
> >  {
> >         return atomic_read(&adev->in_gpu_reset);
> >  }
> > +
> >  #endif
> > diff --git a/drivers/gpu/drm/amd/pm/inc/amdgpu_smu.h b/drivers/gpu/drm/amd/pm/inc/amdgpu_smu.h
> > index 715b4225f5ee..29031eb11d39 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)}
> >
> > +/**
> > + * amdgpu_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 amdgpu_memcpy_trailing(dst, first_dst_member, last_dst_member,    \
> 
> I would change this to smu_memcpy_trailing() for consistency.  Other

Sure; I will send a v3.

> than that, it the patch looks good to me.  Did you want me to pick
> this up or do you want to keep this with the other patches in your
> series?

Since this has no external dependencies, it's probably best to go via
your tree.

Thanks!

-Kees

> 
> Thanks!
> 
> Alex
> 
> > +                              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..bda8fc12c91f 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));
> > -
> > +               amdgpu_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..88a4a2aed48e 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));
> > +               amdgpu_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));
> > +               amdgpu_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..d46b892846f6 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));
> > +               amdgpu_memcpy_trailing(smc_pptable, GfxMaxCurrent, reserved,
> > +                                      smc_dpm_table, GfxMaxCurrent);
> >         return 0;
> >  }
> >
> > --
> > 2.30.2
> >

-- 
Kees Cook

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