From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Peilin Ye <yepeilin.cs@gmail.com>
Cc: "Mauro Carvalho Chehab" <mchehab@kernel.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
syzkaller-bugs@googlegroups.com,
"Hans Verkuil" <hverkuil-cisco@xs4all.nl>,
"Sakari Ailus" <sakari.ailus@linux.intel.com>,
"Arnd Bergmann" <arnd@arndb.de>,
"Vandana BN" <bnvandana@gmail.com>,
"Ezequiel Garcia" <ezequiel@collabora.com>,
"Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>,
linux-kernel-mentees@lists.linuxfoundation.org,
linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [Linux-kernel-mentees] [PATCH v2] media/v4l2-core: Fix kernel-infoleak in video_put_user()
Date: Mon, 27 Jul 2020 01:10:56 +0300 [thread overview]
Message-ID: <20200726221056.GJ28704@pendragon.ideasonboard.com> (raw)
In-Reply-To: <20200726220557.102300-1-yepeilin.cs@gmail.com>
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@ideasonboard.com>
> Reported-and-tested-by: syzbot+79d751604cb6f29fbf59@syzkaller.appspotmail.com
> Link: https://syzkaller.appspot.com/bug?extid=79d751604cb6f29fbf59
> Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
> ---
> 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
next prev parent reply other threads:[~2020-07-26 22:11 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-26 16:44 [Linux-kernel-mentees] [PATCH] media/v4l2-core: Fix kernel-infoleak in video_put_user() Peilin Ye
2020-07-26 17:30 ` Laurent Pinchart
2020-07-26 18:07 ` Peilin Ye
2020-07-26 22:08 ` Laurent Pinchart
2020-07-26 22:15 ` Peilin Ye
2020-07-26 18:12 ` Peilin Ye
2020-07-26 22:05 ` [Linux-kernel-mentees] [PATCH v2] " Peilin Ye
2020-07-26 22:10 ` Laurent Pinchart [this message]
2020-07-26 22:16 ` Peilin Ye
2020-07-26 22:27 ` [Linux-kernel-mentees] [PATCH v3] " Peilin Ye
2020-07-27 7:25 ` Arnd Bergmann
2020-07-27 7:56 ` Peilin Ye
2020-07-27 13:16 ` Dan Carpenter
2020-07-27 14:05 ` Arnd Bergmann
2020-07-27 14:14 ` Peilin Ye
2020-07-27 14:20 ` Arnd Bergmann
2020-07-27 14:46 ` Dan Carpenter
2020-07-27 15:30 ` Peilin Ye
2020-07-27 14:43 ` Dan Carpenter
2020-07-27 14:55 ` Arnd Bergmann
2020-07-27 22:04 ` Peilin Ye
2020-07-28 9:00 ` Arnd Bergmann
2020-07-28 10:02 ` Dan Carpenter
2020-07-28 12:22 ` Linus Walleij
2020-07-28 13:06 ` Dan Carpenter
2020-07-28 13:58 ` Arnd Bergmann
2020-07-30 8:07 ` Bartosz Golaszewski
2020-07-30 8:15 ` Arnd Bergmann
2020-07-30 8:38 ` Andy Shevchenko
2020-07-30 9:18 ` Arnd Bergmann
2020-07-30 11:48 ` Andy Shevchenko
2020-07-30 13:49 ` Arnd Bergmann
2020-07-27 8:00 ` [Linux-kernel-mentees] [PATCH v4] " Peilin Ye
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