[25/64] drm/mga/mga_ioc32: Use struct_group() for memcpy() region

Message ID 20210727205855.411487-26-keescook@chromium.org
State New
Headers show
Series
  • Introduce strict memcpy() bounds checking
Related show

Commit Message

Kees Cook July 27, 2021, 8:58 p.m.
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 <keescook@chromium.org>
---
 drivers/gpu/drm/mga/mga_ioc32.c | 30 ++++++++++++++------------
 include/uapi/drm/mga_drm.h      | 37 ++++++++++++++++++++++++---------
 2 files changed, 44 insertions(+), 23 deletions(-)

Comments

Greg Kroah-Hartman July 28, 2021, 5:56 a.m. | #1
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 <keescook@chromium.org>
> ---
>  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?

thanks,

greg k-h
Daniel Vetter July 29, 2021, 12:11 p.m. | #2
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 <keescook@chromium.org>
> > ---
> >  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 <daniel.vetter@ffwll.ch>

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
Kees Cook July 31, 2021, 4:20 a.m. | #3
On Thu, Jul 29, 2021 at 02:11:27PM +0200, Daniel Vetter wrote:
> 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.
> > > [...]
> > 
> > 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?

Ah yeah; it looks like include/uapi/linux/stddef.h is the place for it.

> Anyway mga is very dead, I don't anyone cares.
> 
> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> 
> I'm assuming this goes in through a topic pull from you?

Thanks! Yeah, my intention is to carry this as topic branch for Linus.

-Kees

Patch

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
+
 typedef struct drm_mga_dma_bootstrap {
 	/**
 	 * \name AGP texture region