[PATCH RESEND] media: omap3isp: Use struct_group() for memcpy() region

[PATCH RESEND] media: omap3isp: Use struct_group() for memcpy() region

[Kees Cook]

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. Wrap the target region
in struct_group(). This additionally fixes a theoretical misalignment
of the copy (since the size of "buf" changes between 64-bit and 32-bit,
but this is likely never built for 64-bit).

FWIW, I think this code is totally broken on 64-bit (which appears to
not be a "real" build configuration): it would either always fail (with
an uninitialized data->buf_size) or would cause corruption in userspace
due to the copy_to_user() in the call path against an uninitialized
data->buf value:

omap3isp_stat_request_statistics_time32(...)
    struct omap3isp_stat_data data64;
    ...
    omap3isp_stat_request_statistics(stat, &data64);

int omap3isp_stat_request_statistics(struct ispstat *stat,
                                     struct omap3isp_stat_data *data)
    ...
    buf = isp_stat_buf_get(stat, data);

static struct ispstat_buffer *isp_stat_buf_get(struct ispstat *stat,
                                               struct omap3isp_stat_data *data)
...
    if (buf->buf_size > data->buf_size) {
            ...
            return ERR_PTR(-EINVAL);
    }
    ...
    rval = copy_to_user(data->buf,
                        buf->virt_addr,
                        buf->buf_size);

Regardless, additionally initialize data64 to be zero-filled to avoid
undefined behavior.

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: linux-media@vger.kernel.org
Fixes: 378e3f81cb56 ("media: omap3isp: support 64-bit version of omap3isp_stat_data")
Cc: stable@vger.kernel.org
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/lkml/20211215220505.GB21862@embeddedor
Signed-off-by: Kees Cook <keescook@chromium.org>
---
I will carry this in my tree unless someone else wants to pick it up. It's
one of the last remaining clean-ups needed for the next step in memcpy()
hardening.
---
 drivers/media/platform/omap3isp/ispstat.c |  5 +++--
 include/uapi/linux/omap3isp.h             | 21 +++++++++++++--------
 2 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/drivers/media/platform/omap3isp/ispstat.c b/drivers/media/platform/omap3isp/ispstat.c
index 5b9b57f4d9bf..68cf68dbcace 100644
--- a/drivers/media/platform/omap3isp/ispstat.c
+++ b/drivers/media/platform/omap3isp/ispstat.c
@@ -512,7 +512,7 @@ int omap3isp_stat_request_statistics(struct ispstat *stat,
 int omap3isp_stat_request_statistics_time32(struct ispstat *stat,
 					struct omap3isp_stat_data_time32 *data)
 {
-	struct omap3isp_stat_data data64;
+	struct omap3isp_stat_data data64 = { };
 	int ret;
 
 	ret = omap3isp_stat_request_statistics(stat, &data64);
@@ -521,7 +521,8 @@ int omap3isp_stat_request_statistics_time32(struct ispstat *stat,
 
 	data->ts.tv_sec = data64.ts.tv_sec;
 	data->ts.tv_usec = data64.ts.tv_usec;
-	memcpy(&data->buf, &data64.buf, sizeof(*data) - sizeof(data->ts));
+	data->buf = (uintptr_t)data64.buf;
+	memcpy(&data->frame, &data64.frame, sizeof(data->frame));
 
 	return 0;
 }
diff --git a/include/uapi/linux/omap3isp.h b/include/uapi/linux/omap3isp.h
index 87b55755f4ff..d9db7ad43890 100644
--- a/include/uapi/linux/omap3isp.h
+++ b/include/uapi/linux/omap3isp.h
@@ -162,6 +162,7 @@ struct omap3isp_h3a_aewb_config {
  * struct omap3isp_stat_data - Statistic data sent to or received from user
  * @ts: Timestamp of returned framestats.
  * @buf: Pointer to pass to user.
+ * @buf_size: Size of buffer.
  * @frame_number: Frame number of requested stats.
  * @cur_frame: Current frame number being processed.
  * @config_counter: Number of the configuration associated with the data.
@@ -176,10 +177,12 @@ struct omap3isp_stat_data {
 	struct timeval ts;
 #endif
 	void __user *buf;
-	__u32 buf_size;
-	__u16 frame_number;
-	__u16 cur_frame;
-	__u16 config_counter;
+	__struct_group(/* no tag */, frame, /* no attrs */,
+		__u32 buf_size;
+		__u16 frame_number;
+		__u16 cur_frame;
+		__u16 config_counter;
+	);
 };
 
 #ifdef __KERNEL__
@@ -189,10 +192,12 @@ struct omap3isp_stat_data_time32 {
 		__s32	tv_usec;
 	} ts;
 	__u32 buf;
-	__u32 buf_size;
-	__u16 frame_number;
-	__u16 cur_frame;
-	__u16 config_counter;
+	__struct_group(/* no tag */, frame, /* no attrs */,
+		__u32 buf_size;
+		__u16 frame_number;
+		__u16 cur_frame;
+		__u16 config_counter;
+	);
 };
 #endif
 
-- 
2.30.2

Re: [PATCH RESEND] media: omap3isp: Use struct_group() for memcpy() region

[Mauro Carvalho Chehab]

Em Mon, 24 Jan 2022 09:29:52 -0800
Kees Cook <keescook@chromium.org> escreveu:

> 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. Wrap the target region
> in struct_group(). This additionally fixes a theoretical misalignment
> of the copy (since the size of "buf" changes between 64-bit and 32-bit,
> but this is likely never built for 64-bit).


> FWIW, I think this code is totally broken on 64-bit (which appears to
> not be a "real" build configuration): it would either always fail (with
> an uninitialized data->buf_size) or would cause corruption in userspace
> due to the copy_to_user() in the call path against an uninitialized
> data->buf value:

It doesn't matter. This driver is specific for TI OMAP3 SoC, which
is Cortex-A8 (32-bits). It only builds on 64 bit due to COMPILE_TEST.

Regards,
Mauro

> 
> omap3isp_stat_request_statistics_time32(...)
>     struct omap3isp_stat_data data64;
>     ...
>     omap3isp_stat_request_statistics(stat, &data64);
> 
> int omap3isp_stat_request_statistics(struct ispstat *stat,
>                                      struct omap3isp_stat_data *data)
>     ...
>     buf = isp_stat_buf_get(stat, data);
> 
> static struct ispstat_buffer *isp_stat_buf_get(struct ispstat *stat,
>                                                struct omap3isp_stat_data *data)
> ...
>     if (buf->buf_size > data->buf_size) {
>             ...
>             return ERR_PTR(-EINVAL);
>     }
>     ...
>     rval = copy_to_user(data->buf,
>                         buf->virt_addr,
>                         buf->buf_size);
> 
> Regardless, additionally initialize data64 to be zero-filled to avoid
> undefined behavior.
> 
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
> Cc: linux-media@vger.kernel.org
> Fixes: 378e3f81cb56 ("media: omap3isp: support 64-bit version of omap3isp_stat_data")
> Cc: stable@vger.kernel.org
> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> Link: https://lore.kernel.org/lkml/20211215220505.GB21862@embeddedor
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> I will carry this in my tree unless someone else wants to pick it up. It's
> one of the last remaining clean-ups needed for the next step in memcpy()
> hardening.
> ---
>  drivers/media/platform/omap3isp/ispstat.c |  5 +++--
>  include/uapi/linux/omap3isp.h             | 21 +++++++++++++--------
>  2 files changed, 16 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/media/platform/omap3isp/ispstat.c b/drivers/media/platform/omap3isp/ispstat.c
> index 5b9b57f4d9bf..68cf68dbcace 100644
> --- a/drivers/media/platform/omap3isp/ispstat.c
> +++ b/drivers/media/platform/omap3isp/ispstat.c
> @@ -512,7 +512,7 @@ int omap3isp_stat_request_statistics(struct ispstat *stat,
>  int omap3isp_stat_request_statistics_time32(struct ispstat *stat,
>  					struct omap3isp_stat_data_time32 *data)
>  {
> -	struct omap3isp_stat_data data64;
> +	struct omap3isp_stat_data data64 = { };
>  	int ret;
>  
>  	ret = omap3isp_stat_request_statistics(stat, &data64);
> @@ -521,7 +521,8 @@ int omap3isp_stat_request_statistics_time32(struct ispstat *stat,
>  
>  	data->ts.tv_sec = data64.ts.tv_sec;
>  	data->ts.tv_usec = data64.ts.tv_usec;
> -	memcpy(&data->buf, &data64.buf, sizeof(*data) - sizeof(data->ts));
> +	data->buf = (uintptr_t)data64.buf;
> +	memcpy(&data->frame, &data64.frame, sizeof(data->frame));
>  
>  	return 0;
>  }
> diff --git a/include/uapi/linux/omap3isp.h b/include/uapi/linux/omap3isp.h
> index 87b55755f4ff..d9db7ad43890 100644
> --- a/include/uapi/linux/omap3isp.h
> +++ b/include/uapi/linux/omap3isp.h
> @@ -162,6 +162,7 @@ struct omap3isp_h3a_aewb_config {
>   * struct omap3isp_stat_data - Statistic data sent to or received from user
>   * @ts: Timestamp of returned framestats.
>   * @buf: Pointer to pass to user.
> + * @buf_size: Size of buffer.
>   * @frame_number: Frame number of requested stats.
>   * @cur_frame: Current frame number being processed.
>   * @config_counter: Number of the configuration associated with the data.
> @@ -176,10 +177,12 @@ struct omap3isp_stat_data {
>  	struct timeval ts;
>  #endif
>  	void __user *buf;
> -	__u32 buf_size;
> -	__u16 frame_number;
> -	__u16 cur_frame;
> -	__u16 config_counter;
> +	__struct_group(/* no tag */, frame, /* no attrs */,
> +		__u32 buf_size;
> +		__u16 frame_number;
> +		__u16 cur_frame;
> +		__u16 config_counter;
> +	);
>  };
>  
>  #ifdef __KERNEL__
> @@ -189,10 +192,12 @@ struct omap3isp_stat_data_time32 {
>  		__s32	tv_usec;
>  	} ts;
>  	__u32 buf;
> -	__u32 buf_size;
> -	__u16 frame_number;
> -	__u16 cur_frame;
> -	__u16 config_counter;
> +	__struct_group(/* no tag */, frame, /* no attrs */,
> +		__u32 buf_size;
> +		__u16 frame_number;
> +		__u16 cur_frame;
> +		__u16 config_counter;
> +	);
>  };
>  #endif
>  



Thanks,
Mauro

Re: [PATCH RESEND] media: omap3isp: Use struct_group() for memcpy() region

[Laurent Pinchart]

Hi Kees,

Thank you for the patch.

On Mon, Jan 24, 2022 at 09:29:52AM -0800, 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. Wrap the target region
> in struct_group(). This additionally fixes a theoretical misalignment
> of the copy (since the size of "buf" changes between 64-bit and 32-bit,
> but this is likely never built for 64-bit).
> 
> FWIW, I think this code is totally broken on 64-bit (which appears to
> not be a "real" build configuration): it would either always fail (with
> an uninitialized data->buf_size) or would cause corruption in userspace
> due to the copy_to_user() in the call path against an uninitialized
> data->buf value:
> 
> omap3isp_stat_request_statistics_time32(...)
>     struct omap3isp_stat_data data64;
>     ...
>     omap3isp_stat_request_statistics(stat, &data64);
> 
> int omap3isp_stat_request_statistics(struct ispstat *stat,
>                                      struct omap3isp_stat_data *data)
>     ...
>     buf = isp_stat_buf_get(stat, data);
> 
> static struct ispstat_buffer *isp_stat_buf_get(struct ispstat *stat,
>                                                struct omap3isp_stat_data *data)
> ...
>     if (buf->buf_size > data->buf_size) {
>             ...
>             return ERR_PTR(-EINVAL);
>     }
>     ...
>     rval = copy_to_user(data->buf,
>                         buf->virt_addr,
>                         buf->buf_size);
> 
> Regardless, additionally initialize data64 to be zero-filled to avoid
> undefined behavior.
> 
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
> Cc: linux-media@vger.kernel.org
> Fixes: 378e3f81cb56 ("media: omap3isp: support 64-bit version of omap3isp_stat_data")
> Cc: stable@vger.kernel.org
> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> Link: https://lore.kernel.org/lkml/20211215220505.GB21862@embeddedor
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> I will carry this in my tree unless someone else wants to pick it up. It's
> one of the last remaining clean-ups needed for the next step in memcpy()
> hardening.

I don't mind either way. Sakari, do you want to pick the patch up ?

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  drivers/media/platform/omap3isp/ispstat.c |  5 +++--
>  include/uapi/linux/omap3isp.h             | 21 +++++++++++++--------
>  2 files changed, 16 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/media/platform/omap3isp/ispstat.c b/drivers/media/platform/omap3isp/ispstat.c
> index 5b9b57f4d9bf..68cf68dbcace 100644
> --- a/drivers/media/platform/omap3isp/ispstat.c
> +++ b/drivers/media/platform/omap3isp/ispstat.c
> @@ -512,7 +512,7 @@ int omap3isp_stat_request_statistics(struct ispstat *stat,
>  int omap3isp_stat_request_statistics_time32(struct ispstat *stat,
>  					struct omap3isp_stat_data_time32 *data)
>  {
> -	struct omap3isp_stat_data data64;
> +	struct omap3isp_stat_data data64 = { };
>  	int ret;
>  
>  	ret = omap3isp_stat_request_statistics(stat, &data64);
> @@ -521,7 +521,8 @@ int omap3isp_stat_request_statistics_time32(struct ispstat *stat,
>  
>  	data->ts.tv_sec = data64.ts.tv_sec;
>  	data->ts.tv_usec = data64.ts.tv_usec;
> -	memcpy(&data->buf, &data64.buf, sizeof(*data) - sizeof(data->ts));
> +	data->buf = (uintptr_t)data64.buf;
> +	memcpy(&data->frame, &data64.frame, sizeof(data->frame));
>  
>  	return 0;
>  }
> diff --git a/include/uapi/linux/omap3isp.h b/include/uapi/linux/omap3isp.h
> index 87b55755f4ff..d9db7ad43890 100644
> --- a/include/uapi/linux/omap3isp.h
> +++ b/include/uapi/linux/omap3isp.h
> @@ -162,6 +162,7 @@ struct omap3isp_h3a_aewb_config {
>   * struct omap3isp_stat_data - Statistic data sent to or received from user
>   * @ts: Timestamp of returned framestats.
>   * @buf: Pointer to pass to user.
> + * @buf_size: Size of buffer.
>   * @frame_number: Frame number of requested stats.
>   * @cur_frame: Current frame number being processed.
>   * @config_counter: Number of the configuration associated with the data.
> @@ -176,10 +177,12 @@ struct omap3isp_stat_data {
>  	struct timeval ts;
>  #endif
>  	void __user *buf;
> -	__u32 buf_size;
> -	__u16 frame_number;
> -	__u16 cur_frame;
> -	__u16 config_counter;
> +	__struct_group(/* no tag */, frame, /* no attrs */,
> +		__u32 buf_size;
> +		__u16 frame_number;
> +		__u16 cur_frame;
> +		__u16 config_counter;
> +	);
>  };
>  
>  #ifdef __KERNEL__
> @@ -189,10 +192,12 @@ struct omap3isp_stat_data_time32 {
>  		__s32	tv_usec;
>  	} ts;
>  	__u32 buf;
> -	__u32 buf_size;
> -	__u16 frame_number;
> -	__u16 cur_frame;
> -	__u16 config_counter;
> +	__struct_group(/* no tag */, frame, /* no attrs */,
> +		__u32 buf_size;
> +		__u16 frame_number;
> +		__u16 cur_frame;
> +		__u16 config_counter;
> +	);
>  };
>  #endif
>  

-- 
Regards,

Laurent Pinchart

Re: [PATCH RESEND] media: omap3isp: Use struct_group() for memcpy() region

[Sakari Ailus]

Hi Mauro,

On Tue, Jan 25, 2022 at 09:24:26AM +0100, Mauro Carvalho Chehab wrote:
> Em Mon, 24 Jan 2022 09:29:52 -0800
> Kees Cook <keescook@chromium.org> escreveu:
> 
> > 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. Wrap the target region
> > in struct_group(). This additionally fixes a theoretical misalignment
> > of the copy (since the size of "buf" changes between 64-bit and 32-bit,
> > but this is likely never built for 64-bit).
> 
> 
> > FWIW, I think this code is totally broken on 64-bit (which appears to
> > not be a "real" build configuration): it would either always fail (with
> > an uninitialized data->buf_size) or would cause corruption in userspace
> > due to the copy_to_user() in the call path against an uninitialized
> > data->buf value:
> 
> It doesn't matter. This driver is specific for TI OMAP3 SoC, which
> is Cortex-A8 (32-bits). It only builds on 64 bit due to COMPILE_TEST.

I agree that "it doesn't matter" in any real configuration. But if it's
this easy to address omap3isp driver behaving nicely with compile test,
then this is definitely worth merging.

I'll pick the patch to my tree.

-- 
Kind regards,

Sakari Ailus