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drm/mga/mga_ioc32: Use struct_group() for memcpy() region

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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 is a UAPI header, __struct_group() is used
directly.

Cc: David Airlie <airlied@linux.ie>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Link: https://lore.kernel.org/lkml/YQKa76A6XuFqgM03@phenom.ffwll.local
This commit is contained in:
Kees Cook 2021-05-24 23:55:11 -07:00
parent 43d83af8a5
commit 10579b75e0
2 changed files with 26 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
drivers/gpu/drm/mga/mga_ioc32.c
View File

@ -38,16 +38,18 @@
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, 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];
);
u32 fb_offset;
u32 mmio_offset;
u32 status_offset;
@ -67,9 +69,8 @@ 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;

22
include/uapi/drm/mga_drm.h
View File

@ -279,20 +279,22 @@ typedef struct drm_mga_init {
unsigned long sarea_priv_offset;
int chipset;
int sgram;
__struct_group(/* no tag */, always32bit, /* no attrs */,
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, front_pitch;
unsigned int back_offset, back_pitch;
unsigned int depth_cpp;
unsigned int depth_offset, depth_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];
unsigned int texture_offset[MGA_NR_TEX_HEAPS];
unsigned int texture_size[MGA_NR_TEX_HEAPS];
);
unsigned long fb_offset;
unsigned long mmio_offset;