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From: Kees Cook <keescook@chromium.org>
To: linux-kernel@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>,
	Daniel Vetter <daniel@ffwll.ch>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Daniel Micay <danielmicay@gmail.com>,
	Francis Laniel <laniel_francis@privacyrequired.com>,
	Bart Van Assche <bvanassche@acm.org>,
	David Gow <davidgow@google.com>,
	linux-mm@kvack.org, clang-built-linux@googlegroups.com,
	linux-hardening@vger.kernel.org
Subject: [PATCH for-next 08/25] drm/mga/mga_ioc32: Use struct_group() for memcpy() region
Date: Sun, 22 Aug 2021 00:51:05 -0700	[thread overview]
Message-ID: <20210822075122.864511-9-keescook@chromium.org> (raw)
In-Reply-To: <20210822075122.864511-1-keescook@chromium.org>

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.

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
---
 drivers/gpu/drm/mga/mga_ioc32.c | 27 ++++++++++++++-------------
 include/uapi/drm/mga_drm.h      | 22 ++++++++++++----------
 2 files changed, 26 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/mga/mga_ioc32.c b/drivers/gpu/drm/mga/mga_ioc32.c
index 4fd4de16cd32..894472921c30 100644
--- a/drivers/gpu/drm/mga/mga_ioc32.c
+++ b/drivers/gpu/drm/mga/mga_ioc32.c
@@ -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;
diff --git a/include/uapi/drm/mga_drm.h b/include/uapi/drm/mga_drm.h
index 8c4337548ab5..bb31567e66c0 100644
--- a/include/uapi/drm/mga_drm.h
+++ b/include/uapi/drm/mga_drm.h
@@ -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;
-- 
2.30.2


  parent reply	other threads:[~2021-08-22  7:51 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-22  7:50 [PATCH for-next 00/25] Prepare for better FORTIFY_SOURCE Kees Cook
2021-08-22  7:50 ` [PATCH for-next 01/25] scsi: ibmvscsi: Avoid multi-field memset() overflow by aiming at srp Kees Cook
2021-08-22  7:50 ` [PATCH for-next 02/25] powerpc: Split memset() to avoid multi-field overflow Kees Cook
2021-08-22  7:51 ` [PATCH for-next 03/25] stddef: Fix kerndoc for sizeof_field() and offsetofend() Kees Cook
2021-08-22  7:51 ` [PATCH for-next 04/25] stddef: Introduce struct_group() helper macro Kees Cook
2021-08-22  7:51 ` [PATCH for-next 05/25] cxl/core: Replace unions with struct_group() Kees Cook
2021-08-22  7:51 ` [PATCH for-next 06/25] bnxt_en: Use struct_group_attr() for memcpy() region Kees Cook
2021-08-22  7:51 ` [PATCH for-next 07/25] iommu/amd: Use struct_group() " Kees Cook
2021-08-22  7:51 ` Kees Cook [this message]
2021-08-22  7:51 ` [PATCH for-next 09/25] HID: cp2112: " Kees Cook
2021-08-22  7:51 ` [PATCH for-next 10/25] HID: roccat: Use struct_group() to zero kone_mouse_event Kees Cook
2021-08-22  7:51 ` [PATCH for-next 11/25] can: flexcan: Use struct_group() to zero struct flexcan_regs regions Kees Cook
2021-08-22  7:51 ` [PATCH for-next 12/25] cm4000_cs: Use struct_group() to zero struct cm4000_dev region Kees Cook
2021-08-22  7:51 ` [PATCH for-next 13/25] compiler_types.h: Remove __compiletime_object_size() Kees Cook
2021-08-23  6:43   ` Rasmus Villemoes
2021-08-25 19:43     ` Nick Desaulniers
2021-08-22  7:51 ` [PATCH for-next 14/25] lib/string: Move helper functions out of string.c Kees Cook
2021-08-25 21:48   ` Nick Desaulniers
2021-08-26  2:47     ` Kees Cook
2021-08-26 18:08       ` Nick Desaulniers
2021-08-22  7:51 ` [PATCH for-next 15/25] fortify: Move remaining fortify helpers into fortify-string.h Kees Cook
2021-08-25 21:59   ` Nick Desaulniers
2021-08-22  7:51 ` [PATCH for-next 16/25] fortify: Explicitly disable Clang support Kees Cook
2021-08-25 19:41   ` Nick Desaulniers
2021-08-22  7:51 ` [PATCH for-next 17/25] fortify: Fix dropped strcpy() compile-time write overflow check Kees Cook
2021-08-25 21:55   ` Nick Desaulniers
2021-08-22  7:51 ` [PATCH for-next 18/25] fortify: Prepare to improve strnlen() and strlen() warnings Kees Cook
2021-08-25 22:01   ` Nick Desaulniers
2021-08-22  7:51 ` [PATCH for-next 19/25] fortify: Allow strlen() and strnlen() to pass compile-time known lengths Kees Cook
2021-08-25 22:05   ` Nick Desaulniers
2021-08-26  2:56     ` Kees Cook
2021-08-26 18:02       ` Nick Desaulniers
2021-08-22  7:51 ` [PATCH for-next 20/25] fortify: Add compile-time FORTIFY_SOURCE tests Kees Cook
2021-08-22  7:51 ` [PATCH for-next 21/25] lib: Introduce CONFIG_TEST_MEMCPY Kees Cook
2021-08-24  7:00   ` David Gow
2021-08-25  2:32     ` Kees Cook
2021-10-18 15:46   ` Arnd Bergmann
2021-10-18 19:28     ` Kees Cook
2021-08-22  7:51 ` [PATCH for-next 22/25] string.h: Introduce memset_after() for wiping trailing members/padding Kees Cook
2021-08-22  7:51 ` [PATCH for-next 23/25] xfrm: Use memset_after() to clear padding Kees Cook
2021-08-22  7:51 ` [PATCH for-next 24/25] string.h: Introduce memset_startat() for wiping trailing members and padding Kees Cook
2021-08-22  7:51 ` [PATCH for-next 25/25] btrfs: Use memset_startat() to clear end of struct Kees Cook

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