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Subject[Linux-kernel-mentees] [PATCH] media/v4l2-core: Fix kernel-infoleak in video_put_user()
Date
video_put_user() is copying uninitialized stack memory to userspace. Fix
it by initializing `vb32` using memset().

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>
---
drivers/media/v4l2-core/v4l2-ioctl.c | 32 +++++++++++++++-------------
1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index a556880f225a..08909f58dc80 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -3210,21 +3210,23 @@ 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;
--
2.25.1
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