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References: <20221102152540.2389891-1-nathan@kernel.org> <20221102152540.2389891-2-nathan@kernel.org>
 <202211020842.8B8E29F8@keescook>
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From:   Alex Deucher <alexdeucher@gmail.com>
Date:   Wed, 2 Nov 2022 12:15:20 -0400
Message-ID: <CADnq5_NFtZHzOC2o1yq6VjqT8DYB+q200R_xjf+b1qZonRh4=Q@mail.gmail.com>
Subject: Re: [PATCH 2/2] drm/amdgpu: Fix type of second parameter in
 odn_edit_dpm_table() callback
To:     Kees Cook <keescook@chromium.org>
Cc:     Nathan Chancellor <nathan@kernel.org>, llvm@lists.linux.dev,
        Tom Rix <trix@redhat.com>, "Pan, Xinhui" <Xinhui.Pan@amd.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        patches@lists.linux.dev, amd-gfx@lists.freedesktop.org,
        Sami Tolvanen <samitolvanen@google.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>
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Precedence: bulk

Applied the series.  Thanks!

Alex

On Wed, Nov 2, 2022 at 11:43 AM Kees Cook <keescook@chromium.org> wrote:
>
> On Wed, Nov 02, 2022 at 08:25:40AM -0700, Nathan Chancellor wrote:
> > With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
> > indirect call targets are validated against the expected function
> > pointer prototype to make sure the call target is valid to help mitigat=
e
> > ROP attacks. If they are not identical, there is a failure at run time,
> > which manifests as either a kernel panic or thread getting killed. A
> > proposed warning in clang aims to catch these at compile time, which
> > reveals:
> >
> >   drivers/gpu/drm/amd/amdgpu/../pm/swsmu/amdgpu_smu.c:3008:29: error: i=
ncompatible function pointer types initializing 'int (*)(void *, uint32_t, =
long *, uint32_t)' (aka 'int (*)(void *, unsigned int, long *, unsigned int=
)') with an expression of type 'int (void *, enum PP_OD_DPM_TABLE_COMMAND, =
long *, uint32_t)' (aka 'int (void *, enum PP_OD_DPM_TABLE_COMMAND, long *,=
 unsigned int)') [-Werror,-Wincompatible-function-pointer-types-strict]
> >           .odn_edit_dpm_table      =3D smu_od_edit_dpm_table,
> >                                      ^~~~~~~~~~~~~~~~~~~~~
> >   1 error generated.
> >
> > There are only two implementations of ->odn_edit_dpm_table() in 'struct
> > amd_pm_funcs': smu_od_edit_dpm_table() and pp_odn_edit_dpm_table(). One
> > has a second parameter type of 'enum PP_OD_DPM_TABLE_COMMAND' and the
> > other uses 'u32'. Ultimately, smu_od_edit_dpm_table() calls
> > ->od_edit_dpm_table() from 'struct pptable_funcs' and
> > pp_odn_edit_dpm_table() calls ->odn_edit_dpm_table() from 'struct
> > pp_hwmgr_func', which both have a second parameter type of 'enum
> > PP_OD_DPM_TABLE_COMMAND'.
> >
> > Update the type parameter in both the prototype in 'struct amd_pm_funcs=
'
> > and pp_odn_edit_dpm_table() to 'enum PP_OD_DPM_TABLE_COMMAND', which
> > cleans up the warning.
> >
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1750
> > Reported-by: Sami Tolvanen <samitolvanen@google.com>
> > Signed-off-by: Nathan Chancellor <nathan@kernel.org>
>
> Reviewed-by: Kees Cook <keescook@chromium.org>
>
> --
> Kees Cook