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

[PATCH] 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.

Fixes: 378e3f81cb56 ("media: omap3isp: support 64-bit version of omap3isp_stat_data")
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 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..9a6b3ed11455 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 type */, 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 type */, frame, /* no attrs */,
+		__u32 buf_size;
+		__u16 frame_number;
+		__u16 cur_frame;
+		__u16 config_counter;
+	);
 };
 #endif
 
-- 
2.30.2

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

[Gustavo A. R. Silva]

On Thu, Nov 18, 2021 at 10:43:52AM -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.
> 
> Fixes: 378e3f81cb56 ("media: omap3isp: support 64-bit version of omap3isp_stat_data")
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  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;

Shouldn't this be

	data->buf = (uintptr_t)(void *)data64.buf;

instead?

--
Gustavo

> +	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..9a6b3ed11455 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 type */, 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 type */, frame, /* no attrs */,
> +		__u32 buf_size;
> +		__u16 frame_number;
> +		__u16 cur_frame;
> +		__u16 config_counter;
> +	);
>  };
>  #endif
>  
> -- 
> 2.30.2
> 
> 
> 
> 

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

[Kees Cook]

On Mon, Dec 13, 2021 at 05:24:16PM -0600, Gustavo A. R. Silva wrote:
> On Thu, Nov 18, 2021 at 10:43:52AM -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.
> > 
> > Fixes: 378e3f81cb56 ("media: omap3isp: support 64-bit version of omap3isp_stat_data")
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> > ---
> >  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;
> 
> Shouldn't this be
> 
> 	data->buf = (uintptr_t)(void *)data64.buf;
> 
> instead?

This is already a void *:

struct omap3isp_stat_data {
	...
        void __user *buf;
};

But I agree, the mix of structures in here is confusing! :)

-Kees

-- 
Kees Cook

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

[Gustavo A. R. Silva]

On Wed, Dec 15, 2021 at 09:38:55AM -0800, Kees Cook wrote:
> On Mon, Dec 13, 2021 at 05:24:16PM -0600, Gustavo A. R. Silva wrote:
> > On Thu, Nov 18, 2021 at 10:43:52AM -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.
> > > 
> > > Fixes: 378e3f81cb56 ("media: omap3isp: support 64-bit version of omap3isp_stat_data")
> > > Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

> > > ---
> > >  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;
> > 
> > Shouldn't this be
> > 
> > 	data->buf = (uintptr_t)(void *)data64.buf;
> > 
> > instead?
> 
> This is already a void *:
> 
> struct omap3isp_stat_data {
> 	...
>         void __user *buf;
> };
> 
> But I agree, the mix of structures in here is confusing! :)

Yep; you're right. :)

Thanks
--
Gustavo