[PATCH 01/64] media: omap3isp: Extract struct group for memcpy() region

Kees Cook
2021-07-27T21:01:43Z

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));

return 0;
}
diff --git a/include/uapi/linux/omap3isp.h b/include/uapi/linux/omap3isp.h
index 87b55755f4ff..0a16af91621f 100644
--- a/include/uapi/linux/omap3isp.h
+++ b/include/uapi/linux/omap3isp.h
@@ -159,13 +159,25 @@ 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.
+ * struct omap3isp_stat_frame - Statistic data without timestamp nor pointer.
+ * @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.
*/
+struct omap3isp_stat_frame {
+ __u32 buf_size;
+ __u16 frame_number;
+ __u16 cur_frame;
+ __u16 config_counter;
+};
+
+/**
+ * struct omap3isp_stat_data - Statistic data sent to or received from user
+ * @ts: Timestamp of returned framestats.
+ * @buf: Pointer to pass to user.
+ * @frame: Statistic data for frame.
+ */
struct omap3isp_stat_data {
#ifdef __KERNEL__
struct {
@@ -176,10 +188,15 @@ struct omap3isp_stat_data {
struct timeval ts;
#endif
void __user *buf;
- __u32 buf_size;
- __u16 frame_number;
- __u16 cur_frame;
- __u16 config_counter;
+ union {
+ struct {
+ __u32 buf_size;
+ __u16 frame_number;
+ __u16 cur_frame;
+ __u16 config_counter;
+ };
+ struct omap3isp_stat_frame frame;
+ };
};

#ifdef __KERNEL__
@@ -189,10 +206,15 @@ struct omap3isp_stat_data_time32 {
__s32 tv_usec;
} ts;
__u32 buf;
- __u32 buf_size;
- __u16 frame_number;
- __u16 cur_frame;
- __u16 config_counter;
+ union {
+ struct {
+ __u32 buf_size;
+ __u16 frame_number;
+ __u16 cur_frame;
+ __u16 config_counter;
+ };
+ struct omap3isp_stat_frame frame;
+ };
};
#endif

--
2.30.2