Re: [PATCH v4 0/3] hw/block/fdc: Fix CVE-2021-20196

[Philippe Mathieu-Daudé]

On 12/10/21 14:42, Kevin Wolf wrote:
> Am 24.11.2021 um 17:15 hat Philippe Mathieu-Daudé geschrieben:
>> Since v3:
>> - Preliminary extract blk_create_empty_drive()
>> - qtest checks qtest_check_clang_sanitizer() enabled
>> - qtest uses null-co:// driver instead of file
>>
>> Philippe Mathieu-Daudé (3):
>>   hw/block/fdc: Extract blk_create_empty_drive()
>>   hw/block/fdc: Kludge missing floppy drive to fix CVE-2021-20196
>>   tests/qtest/fdc-test: Add a regression test for CVE-2021-20196
> 
> If I may ask a meta question: No doubt that this is a bug and it's good
> that we fixed it, but why was it assigned a CVE?

No clue, I suppose this is audited and handled by qemu-security@ team
members. Cc'ing them.

> Any guest can legitimately shut down and we don't consider that a denial
> of service. This bug was essentially just another undocumented way for
> the guest kernel to shut down, as unprivileged users in the guest can't
> normally access the I/O ports of the floppy controller. I don't think we
> generally consider guests killing themselves a security problem as long
> as it requires kernel or root privileges in the guest.

Agreed.