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

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