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Re: [PATCH-for-6.0? v2] mptsas: Remove unused MPTSASState 'pending' fiel
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From: |
Philippe Mathieu-Daudé |
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Subject: |
Re: [PATCH-for-6.0? v2] mptsas: Remove unused MPTSASState 'pending' field (CVE-2021-3392) |
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Date: |
Mon, 19 Apr 2021 15:42:25 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 |
On 4/19/21 3:32 PM, Peter Maydell wrote:
> On Sun, 18 Apr 2021 at 06:30, Philippe Mathieu-Daudé <philmd@redhat.com>
> wrote:
>>
>> From: Michael Tokarev <mjt@tls.msk.ru>
>>
>> While processing SCSI i/o requests in mptsas_process_scsi_io_request(),
>> the Megaraid emulator appends new MPTSASRequest object 'req' to
>> the 's->pending' queue. In case of an error, this same object gets
>> dequeued in mptsas_free_request() only if SCSIRequest object
>> 'req->sreq' is initialised. This may lead to a use-after-free issue.
>>
>> Since s->pending is actually not used, simply remove it from
>> MPTSASState.
>>
>> Cc: qemu-stable@nongnu.org
>> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
>> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>> Message-Id: <20210416102243.1293871-1-mjt@msgid.tls.msk.ru>
>> Reported-by: Cheolwoo Myung <cwmyung@snu.ac.kr>
>> BugLink: https://bugs.launchpad.net/qemu/+bug/1914236 (CVE-2021-3392)
>> Fixes: e351b826112 ("hw: Add support for LSI SAS1068 (mptsas) device")
>> [PMD: Reworded description, added more tags]
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>> ---
>> Supersedes: <20210416102243.1293871-1-mjt@msgid.tls.msk.ru>
>>
>> MJT patch:
>> https://www.mail-archive.com/qemu-devel@nongnu.org/msg799236.html
>>
>> Since rc4 is soon, I'm directly respining his patch with my comments
>> addressed.
>>
>> This is not a new regression (present since QEMU v2.6.0) but is a
>> CVE...
>>
>> PJP first patch:
>> https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg02660.html
>> ---
>> hw/scsi/mptsas.h | 1 -
>> hw/scsi/mptsas.c | 4 ----
>> 2 files changed, 5 deletions(-)
>
> This fails to compile:
>
> ../../hw/scsi/mptsas.c: In function ‘mptsas_free_request’:
> ../../hw/scsi/mptsas.c:254:18: error: unused variable ‘s’
> [-Werror=unused-variable]
> MPTSASState *s = req->dev;
> ^
> cc1: all warnings being treated as errors
What a shame... Sorry, v3 coming.