On Tue, Jul 27, 2021 at 07:55:46PM -0500, Gustavo A. R. Silva wrote:
On Tue, Jul 27, 2021 at 01:57:52PM -0700, 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 a common named structure. 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 | 44 +++++++++++++++++------ 2 files changed, 36 insertions(+), 13 deletions(-)
diff --git a/drivers/media/platform/omap3isp/ispstat.c b/drivers/media/platform/omap3isp/ispstat.c index 5b9b57f4d9bf..ea8222fed38e 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.buf, sizeof(data->frame));
I think this should be:
memcpy(..., &data64.frame, ...);
instead.
Whoops; thanks! This is what I get for temporarily silencing the read-overflow warnings. :)
-Kees