From: John Snow <jsnow@redhat.com>
To: Alexander Bulekov <alxndr@bu.edu>, P J P <ppandit@redhat.com>
Cc: Gaoning Pan <pgn@zju.edu.cn>,
QEMU Developers <qemu-devel@nongnu.org>,
Prasad J Pandit <pjp@fedoraproject.org>
Subject: Re: [PATCH] fdc: check drive block device before usage (CVE-2021-20196)
Date: Mon, 17 May 2021 15:41:58 -0400 [thread overview]
Message-ID: <3fc646ae-e34d-dbcd-204b-156f99ce75c2@redhat.com> (raw)
In-Reply-To: <20210123175245.rpckqnoihjtsv6lp@mozz.bu.edu>
On 1/23/21 12:52 PM, Alexander Bulekov wrote:
> On 210123 1247, Alexander Bulekov wrote:
>> Hello,
>> Here is a reproducer for this bug found by the OSS-Fuzz fuzzer:
>>
>> cat << EOF | qemu-system-i386 -display none -machine accel=qtest \
>> -m 512M -machine pc -device floppy,unit=1,id=floppy0,drive=disk0 \
>> -drive id=disk0,file=null-co://,file.read-zeroes=on,if=none,format=raw \
>> -qtest stdio
>> outw 0x3f4 0x2500
>> outb 0x3f5 0x81
>> outb 0x3f5 0x0
>> outb 0x3f5 0x0
>> outb 0x3f5 0x0
>> outw 0x3f4 0x0
>> outw 0x3f4 0x4000
>> outw 0x3f4 0x13
>> outb 0x3f5 0x1
>> outw 0x3f2 0x1405
>> outw 0x3f4 0x0
>> EOF
>>
> Oops there's a mistake there. Fixed:
>
> cat << EOF | ./qemu-system-i386 -display none -machine accel=qtest \
> -m 512M -machine pc -device floppy,unit=1,id=floppy0,drive=disk0 \
> -drive id=disk0,file=null-co://,file.read-zeroes=on,if=none,format=raw \
> -qtest stdio
> outw 0x3f4 0x2500
> outb 0x3f5 0x81
> outb 0x3f5 0x0
> outb 0x3f5 0x0
> outb 0x3f5 0x0
> outw 0x3f2 0x14
> outw 0x3f4 0x0
> outw 0x3f4 0x4000
> outw 0x3f4 0x13
> outb 0x3f5 0x1
> outw 0x3f2 0x1405
> outw 0x3f4 0x0
> EOF
>
>> -Alex
>>
This actually still triggers after I apply this patch. It's not the same
bug, or the patch isn't sufficient to address this bug.
--js
next prev parent reply other threads:[~2021-05-17 19:42 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-23 10:03 [PATCH] fdc: check drive block device before usage (CVE-2021-20196) P J P
2021-01-23 17:47 ` Alexander Bulekov
2021-01-23 17:52 ` Alexander Bulekov
2021-05-17 19:41 ` John Snow [this message]
2021-01-30 13:35 ` P J P
2021-05-14 19:23 ` Thomas Huth
2021-05-14 19:26 ` John Snow
2021-05-15 8:49 ` Philippe Mathieu-Daudé
2021-05-17 11:12 ` P J P
2021-05-17 17:14 ` John Snow
2021-05-17 17:56 ` Philippe Mathieu-Daudé
2021-05-17 22:39 ` John Snow
2021-05-18 9:01 ` P J P
2021-05-18 14:18 ` John Snow
2021-05-18 17:24 ` John Snow
2021-05-19 7:32 ` P J P
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