On Tue, Aug 25, 2020 at 12:48:04PM -0400, Peilin Ye wrote:

Hi all,

Link: https://syzkaller.appspot.com/bug?id=f332576321998d36cd07d09c9c1268cfed1895c9

As reported by syzbot, vcs_read_buf() is overflowing `con_buf16`, since
this patch removed the following check:

-		if (count > CON_BUF_SIZE) {
-			count = CON_BUF_SIZE;
-			filled = count - pos;
-		}

Decreasing `count` by `min(HEADER_SIZE - pos, count)` bypasses this check.
Additionally, this patch also removed updates to `skip` and `filled`.

What should we do in order to fix it?

This patch is already reverted, and it has been discussed a bit as to
how to do this properly if you look at the email where this was reported
to us.

thanks,

greg k-h
_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees