Hi Peilin, Thank you for the patch. On Sun, Jul 26, 2020 at 06:05:57PM -0400, Peilin Ye wrote: > video_put_user() is copying uninitialized stack memory to userspace. Fix > it by initializing `ev32` and `vb32` using memset(). How about mentioning that this is caused by the compiler not initializing the holes ? Maybe something along the lines of video_put_user() is copying uninitialized stack memory to userspace due to the compiler not initializing holes in the structures declared on the stack. Fix it by initializing the structures using memset(). Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > Reported-and-tested-by: syzbot+79d751604cb6f29fbf59@xxxxxxxxxxxxxxxxxxxxxxxxx > Link: https://syzkaller.appspot.com/bug?extid=79d751604cb6f29fbf59 > Signed-off-by: Peilin Ye <yepeilin.cs@xxxxxxxxx> > --- > Change in v2: > - Do the same thing for `case VIDIOC_DQEVENT_TIME32`. > > drivers/media/v4l2-core/v4l2-ioctl.c | 50 +++++++++++++++------------- > 1 file changed, 27 insertions(+), 23 deletions(-) > > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c > index a556880f225a..e3a25ea913ac 100644 > --- a/drivers/media/v4l2-core/v4l2-ioctl.c > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c > @@ -3189,14 +3189,16 @@ static int video_put_user(void __user *arg, void *parg, unsigned int cmd) > #ifdef CONFIG_COMPAT_32BIT_TIME > case VIDIOC_DQEVENT_TIME32: { > struct v4l2_event *ev = parg; > - struct v4l2_event_time32 ev32 = { > - .type = ev->type, > - .pending = ev->pending, > - .sequence = ev->sequence, > - .timestamp.tv_sec = ev->timestamp.tv_sec, > - .timestamp.tv_nsec = ev->timestamp.tv_nsec, > - .id = ev->id, > - }; > + struct v4l2_event_time32 ev32; > + > + memset(&ev32, 0, sizeof(ev32)); > + > + ev32.type = ev->type; > + ev32.pending = ev->pending; > + ev32.sequence = ev->sequence; > + ev32.timestamp.tv_sec = ev->timestamp.tv_sec; > + ev32.timestamp.tv_nsec = ev->timestamp.tv_nsec; > + ev32.id = ev->id; > > memcpy(&ev32.u, &ev->u, sizeof(ev->u)); > memcpy(&ev32.reserved, &ev->reserved, sizeof(ev->reserved)); > @@ -3210,21 +3212,23 @@ static int video_put_user(void __user *arg, void *parg, unsigned int cmd) > case VIDIOC_DQBUF_TIME32: > case VIDIOC_PREPARE_BUF_TIME32: { > struct v4l2_buffer *vb = parg; > - struct v4l2_buffer_time32 vb32 = { > - .index = vb->index, > - .type = vb->type, > - .bytesused = vb->bytesused, > - .flags = vb->flags, > - .field = vb->field, > - .timestamp.tv_sec = vb->timestamp.tv_sec, > - .timestamp.tv_usec = vb->timestamp.tv_usec, > - .timecode = vb->timecode, > - .sequence = vb->sequence, > - .memory = vb->memory, > - .m.userptr = vb->m.userptr, > - .length = vb->length, > - .request_fd = vb->request_fd, > - }; > + struct v4l2_buffer_time32 vb32; > + > + memset(&vb32, 0, sizeof(vb32)); > + > + vb32.index = vb->index; > + vb32.type = vb->type; > + vb32.bytesused = vb->bytesused; > + vb32.flags = vb->flags; > + vb32.field = vb->field; > + vb32.timestamp.tv_sec = vb->timestamp.tv_sec; > + vb32.timestamp.tv_usec = vb->timestamp.tv_usec; > + vb32.timecode = vb->timecode; > + vb32.sequence = vb->sequence; > + vb32.memory = vb->memory; > + vb32.m.userptr = vb->m.userptr; > + vb32.length = vb->length; > + vb32.request_fd = vb->request_fd; > > if (copy_to_user(arg, &vb32, sizeof(vb32))) > return -EFAULT; -- Regards, Laurent Pinchart
