linux-kernel - [PATCH 5.8 07/17] media: media/v4l2-core: Fix kernel-infoleak in video_put

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Date:   Fri,  4 Sep 2020 15:30:06 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Arnd Bergmann <arnd@...db.de>,
        Peilin Ye <yepeilin.cs@...il.com>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        syzbot+79d751604cb6f29fbf59@...kaller.appspotmail.com
Subject: [PATCH 5.8 07/17] media: media/v4l2-core: Fix kernel-infoleak in video_put_user()

From: Peilin Ye <yepeilin.cs@...il.com>

commit 4ffb879ea648c2b42da4ca992ed3db87e564af69 upstream.

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 `ev32` and `vb32` using memset().

Reported-and-tested-by: syzbot+79d751604cb6f29fbf59@...kaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=79d751604cb6f29fbf59

Cc: stable@...r.kernel.org
Fixes: 1a6c0b36dd19 ("media: v4l2-core: fix VIDIOC_DQEVENT for time64 ABI")
Fixes: 577c89b0ce72 ("media: v4l2-core: fix v4l2_buffer handling for time64 ABI")
Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Reviewed-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Peilin Ye <yepeilin.cs@...il.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@...all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/media/v4l2-core/v4l2-ioctl.c |   50 ++++++++++++++++++-----------------
 1 file changed, 27 insertions(+), 23 deletions(-)

--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -3186,14 +3186,16 @@ static int video_put_user(void __user *a
 #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));
@@ -3207,21 +3209,23 @@ static int video_put_user(void __user *a
 	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;