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R. Silva" , linux-block@vger.kernel.org, clang-built-linux@googlegroups.com, Keith Packard , linux-hardening@vger.kernel.org, Andrew Morton Subject: Re: [PATCH 25/64] drm/mga/mga_ioc32: Use struct_group() for memcpy() region Message-ID: Mail-Followup-To: Greg Kroah-Hartman , Kees Cook , linux-kbuild@vger.kernel.org, netdev@vger.kernel.org, linux-staging@lists.linux.dev, linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, "Gustavo A. R. Silva" , linux-block@vger.kernel.org, clang-built-linux@googlegroups.com, Keith Packard , linux-hardening@vger.kernel.org, Andrew Morton References: <20210727205855.411487-1-keescook@chromium.org> <20210727205855.411487-26-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Operating-System: Linux phenom 5.10.0-7-amd64 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 28, 2021 at 07:56:40AM +0200, Greg Kroah-Hartman wrote: > On Tue, Jul 27, 2021 at 01:58:16PM -0700, Kees Cook 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. > > > > Use struct_group() in struct drm32_mga_init around members chipset, sgram, > > maccess, fb_cpp, front_offset, front_pitch, back_offset, back_pitch, > > depth_cpp, depth_offset, depth_pitch, texture_offset, and texture_size, > > so they can be referenced together. This will allow memcpy() and sizeof() > > to more easily reason about sizes, improve readability, and avoid future > > warnings about writing beyond the end of chipset. > > > > "pahole" shows no size nor member offset changes to struct drm32_mga_init. > > "objdump -d" shows no meaningful object code changes (i.e. only source > > line number induced differences and optimizations). > > > > Note that since this includes a UAPI header, struct_group() has been > > explicitly redefined local to the header. > > > > Signed-off-by: Kees Cook > > --- > > drivers/gpu/drm/mga/mga_ioc32.c | 30 ++++++++++++++------------ > > include/uapi/drm/mga_drm.h | 37 ++++++++++++++++++++++++--------- > > 2 files changed, 44 insertions(+), 23 deletions(-) > > > > diff --git a/drivers/gpu/drm/mga/mga_ioc32.c b/drivers/gpu/drm/mga/mga_ioc32.c > > index 4fd4de16cd32..fbd0329dbd4f 100644 > > --- a/drivers/gpu/drm/mga/mga_ioc32.c > > +++ b/drivers/gpu/drm/mga/mga_ioc32.c > > @@ -38,16 +38,21 @@ > > typedef struct drm32_mga_init { > > int func; > > u32 sarea_priv_offset; > > - int chipset; > > - int sgram; > > - unsigned int maccess; > > - unsigned int fb_cpp; > > - unsigned int front_offset, front_pitch; > > - unsigned int back_offset, back_pitch; > > - unsigned int depth_cpp; > > - unsigned int depth_offset, depth_pitch; > > - unsigned int texture_offset[MGA_NR_TEX_HEAPS]; > > - unsigned int texture_size[MGA_NR_TEX_HEAPS]; > > + struct_group(always32bit, > > + int chipset; > > + int sgram; > > + unsigned int maccess; > > + unsigned int fb_cpp; > > + unsigned int front_offset; > > + unsigned int front_pitch; > > + unsigned int back_offset; > > + unsigned int back_pitch; > > + unsigned int depth_cpp; > > + unsigned int depth_offset; > > + unsigned int depth_pitch; > > + unsigned int texture_offset[MGA_NR_TEX_HEAPS]; > > + unsigned int texture_size[MGA_NR_TEX_HEAPS]; > > + ); > > u32 fb_offset; > > u32 mmio_offset; > > u32 status_offset; > > @@ -67,9 +72,8 @@ static int compat_mga_init(struct file *file, unsigned int cmd, > > > > init.func = init32.func; > > init.sarea_priv_offset = init32.sarea_priv_offset; > > - memcpy(&init.chipset, &init32.chipset, > > - offsetof(drm_mga_init_t, fb_offset) - > > - offsetof(drm_mga_init_t, chipset)); > > + memcpy(&init.always32bit, &init32.always32bit, > > + sizeof(init32.always32bit)); > > init.fb_offset = init32.fb_offset; > > init.mmio_offset = init32.mmio_offset; > > init.status_offset = init32.status_offset; > > diff --git a/include/uapi/drm/mga_drm.h b/include/uapi/drm/mga_drm.h > > index 8c4337548ab5..61612e5ecab2 100644 > > --- a/include/uapi/drm/mga_drm.h > > +++ b/include/uapi/drm/mga_drm.h > > @@ -265,6 +265,16 @@ typedef struct _drm_mga_sarea { > > #define DRM_IOCTL_MGA_WAIT_FENCE DRM_IOWR(DRM_COMMAND_BASE + DRM_MGA_WAIT_FENCE, __u32) > > #define DRM_IOCTL_MGA_DMA_BOOTSTRAP DRM_IOWR(DRM_COMMAND_BASE + DRM_MGA_DMA_BOOTSTRAP, drm_mga_dma_bootstrap_t) > > > > +#define __struct_group(name, fields) \ > > + union { \ > > + struct { \ > > + fields \ > > + }; \ > > + struct { \ > > + fields \ > > + } name; \ > > + } > > + > > typedef struct _drm_mga_warp_index { > > int installed; > > unsigned long phys_addr; > > @@ -279,20 +289,25 @@ typedef struct drm_mga_init { > > > > unsigned long sarea_priv_offset; > > > > - int chipset; > > - int sgram; > > + __struct_group(always32bit, > > + int chipset; > > + int sgram; > > > > - unsigned int maccess; > > + unsigned int maccess; > > > > - unsigned int fb_cpp; > > - unsigned int front_offset, front_pitch; > > - unsigned int back_offset, back_pitch; > > + unsigned int fb_cpp; > > + unsigned int front_offset; > > + unsigned int front_pitch; > > + unsigned int back_offset; > > + unsigned int back_pitch; > > > > - unsigned int depth_cpp; > > - unsigned int depth_offset, depth_pitch; > > + unsigned int depth_cpp; > > + unsigned int depth_offset; > > + unsigned int depth_pitch; > > > > - unsigned int texture_offset[MGA_NR_TEX_HEAPS]; > > - unsigned int texture_size[MGA_NR_TEX_HEAPS]; > > + unsigned int texture_offset[MGA_NR_TEX_HEAPS]; > > + unsigned int texture_size[MGA_NR_TEX_HEAPS]; > > + ); > > > > unsigned long fb_offset; > > unsigned long mmio_offset; > > @@ -302,6 +317,8 @@ typedef struct drm_mga_init { > > unsigned long buffers_offset; > > } drm_mga_init_t; > > > > +#undef __struct_group > > + > > Why can you use __struct_group in this uapi header, but not the > networking one? If there's others, maybe we can stuff the uapi __struct_group into linux/types.h where all the other __ uapi types hang out? Anyway mga is very dead, I don't anyone cares. Acked-by: Daniel Vetter I'm assuming this goes in through a topic pull from you? I'll leave the drm/amd one to figure out between you and Alex. -Daniel > > thanks, > > greg k-h -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch