svn commit: r366965 - stable/12/usr.sbin/bhyve

[Konstantin Belousov]

On Fri, Oct 23, 2020 at 10:48:14AM +0000, Ryan Moeller wrote:
> Author: freqlabs
> Date: Fri Oct 23 10:48:14 2020
> New Revision: 366965
> URL: https://svnweb.freebsd.org/changeset/base/366965
> 
> Log:
>   MFC r366771:
>   
>   bhyve: Update TX descriptor base address and host mapping on change
>   
>   bhyve sometimes segfaults when using an e1000 NIC with a Windows guest.
>   
>   We are only updating our tdba and cached host mapping when the low address
>   register is written and when tx is set enabled, but not when the high address
>   or length registers are written. It is observed that Windows 10 is occasionally
>   enabling tx first then writing the registers in the order low, high, len. This
>   leaves us with a bogus base address and mapping, which causes a segfault later
>   when we try to copy from a descriptor that has unpredictable garbage in a
>   pointer.
>   
>   Updating the address and mapping when any of those registers change seems to fix
>   that particular issue.

Does this description mean that if guest writes garbage into base, it can
crash monitor ?