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@xxxxxxxxxxxx>
> > ---
> > 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
