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Message-ID: <YfCXB7+XOJ8Ue+rR@pendragon.ideasonboard.com>
Date: Wed, 26 Jan 2022 02:34:15 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Kees Cook <keescook@...omium.org>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
Arnd Bergmann <arnd@...db.de>,
Sakari Ailus <sakari.ailus@...ux.intel.com>,
linux-media@...r.kernel.org, stable@...r.kernel.org,
"Gustavo A . R . Silva" <gustavoars@...nel.org>,
linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH RESEND] media: omap3isp: Use struct_group() for memcpy()
region
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@...asonboard.com>
> Cc: Mauro Carvalho Chehab <mchehab@...nel.org>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Sakari Ailus <sakari.ailus@...ux.intel.com>
> Cc: linux-media@...r.kernel.org
> Fixes: 378e3f81cb56 ("media: omap3isp: support 64-bit version of omap3isp_stat_data")
> Cc: stable@...r.kernel.org
> Reviewed-by: Gustavo A. R. Silva <gustavoars@...nel.org>
> Link: https://lore.kernel.org/lkml/20211215220505.GB21862@embeddedor
> Signed-off-by: Kees Cook <keescook@...omium.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@...asonboard.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
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