From: Kees Cook <keescook@chromium.org>
To: Nathan Chancellor <nathan@kernel.org>
Cc: llvm@lists.linux.dev, Tom Rix <trix@redhat.com>,
Alison Wang <alison.wang@nxp.com>,
Nick Desaulniers <ndesaulniers@google.com>,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
patches@lists.linux.dev, Sami Tolvanen <samitolvanen@google.com>
Subject: Re: [PATCH] drm/fsl-dcu: Fix return type of fsl_dcu_drm_connector_mode_valid()
Date: Wed, 2 Nov 2022 08:43:27 -0700 [thread overview]
Message-ID: <202211020843.A19F75B@keescook> (raw)
In-Reply-To: <20221102154215.78059-1-nathan@kernel.org>
On Wed, Nov 02, 2022 at 08:42:15AM -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 mitigate
> 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/fsl-dcu/fsl_dcu_drm_rgb.c:74:16: error: incompatible function pointer types initializing 'enum drm_mode_status (*)(struct drm_connector *, struct drm_display_mode *)' with an expression of type 'int (struct drm_connector *, struct drm_display_mode *)' [-Werror,-Wincompatible-function-pointer-types-strict]
> .mode_valid = fsl_dcu_drm_connector_mode_valid,
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 1 error generated.
>
> ->mode_valid() in 'struct drm_connector_helper_funcs' expects a return
> type of 'enum drm_mode_status', not 'int'. Adjust the return type of
> fsl_dcu_drm_connector_mode_valid() to match the prototype's to resolve
> the warning and CFI failure.
>
> 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
WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: Nathan Chancellor <nathan@kernel.org>
Cc: Stefan Agner <stefan@agner.ch>, Alison Wang <alison.wang@nxp.com>,
dri-devel@lists.freedesktop.org,
Nick Desaulniers <ndesaulniers@google.com>,
Tom Rix <trix@redhat.com>,
Sami Tolvanen <samitolvanen@google.com>,
llvm@lists.linux.dev, linux-kernel@vger.kernel.org,
patches@lists.linux.dev
Subject: Re: [PATCH] drm/fsl-dcu: Fix return type of fsl_dcu_drm_connector_mode_valid()
Date: Wed, 2 Nov 2022 08:43:27 -0700 [thread overview]
Message-ID: <202211020843.A19F75B@keescook> (raw)
In-Reply-To: <20221102154215.78059-1-nathan@kernel.org>
On Wed, Nov 02, 2022 at 08:42:15AM -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 mitigate
> 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/fsl-dcu/fsl_dcu_drm_rgb.c:74:16: error: incompatible function pointer types initializing 'enum drm_mode_status (*)(struct drm_connector *, struct drm_display_mode *)' with an expression of type 'int (struct drm_connector *, struct drm_display_mode *)' [-Werror,-Wincompatible-function-pointer-types-strict]
> .mode_valid = fsl_dcu_drm_connector_mode_valid,
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 1 error generated.
>
> ->mode_valid() in 'struct drm_connector_helper_funcs' expects a return
> type of 'enum drm_mode_status', not 'int'. Adjust the return type of
> fsl_dcu_drm_connector_mode_valid() to match the prototype's to resolve
> the warning and CFI failure.
>
> 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
next prev parent reply other threads:[~2022-11-02 15:43 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-02 15:42 [PATCH] drm/fsl-dcu: Fix return type of fsl_dcu_drm_connector_mode_valid() Nathan Chancellor
2022-11-02 15:42 ` Nathan Chancellor
2022-11-02 15:43 ` Kees Cook [this message]
2022-11-02 15:43 ` Kees Cook
2022-11-14 22:03 ` Nathan Chancellor
2022-11-14 22:03 ` Nathan Chancellor
2022-11-17 23:19 ` Kees Cook
2022-11-17 23:19 ` Kees Cook
2022-11-18 17:40 ` Kees Cook
2022-11-18 17:40 ` Kees Cook
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