Re: [Qemu-devel] [PATCH for-2.9] nbd/client: fix drop_sync [CVE-2017-2630]

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

07.03.2017 03:10, Philippe Mathieu-Daudé wrote:
> Hi Vladimir,
>
> On 03/06/2017 07:30 PM, Eric Blake wrote:
>> From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>>
>> Comparison symbol is misused. It may lead to memory corruption.
>> Introduced in commit 7d3123e.
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> Message-Id: <20170203154757.36140-6-vsementsov@virtuozzo.com>
>> [eblake: add CVE details]
>> Signed-off-by: Eric Blake <eblake@redhat.com>
>> Reviewed-by: Marc-André Lureau <address@hidden>
>> ---
>>
>> This one still hasn't been merged in; sending separately since the
>> rest of my NBD series is now 2.10 material:
>> https://lists.gnu.org/archive/html/qemu-devel/2017-02/msg04528.html
>>
>>  nbd/client.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/nbd/client.c b/nbd/client.c
>> index 5c9dee3..165b33e 100644
>> --- a/nbd/client.c
>> +++ b/nbd/client.c
>> @@ -94,7 +94,7 @@ static ssize_t drop_sync(QIOChannel *ioc, size_t size)
>>      char small[1024];
>>      char *buffer;
>>
>> -    buffer = sizeof(small) < size ? small : g_malloc(MIN(65536, size));
>> +    buffer = sizeof(small) > size ? small : g_malloc(MIN(65536, size));
>
> here ">=" seems correct/safe.
> (if size is 1024, use small stack buffer too).

Agree.

>
>>      while (size > 0) {
>>          ssize_t count = read_sync(ioc, buffer, MIN(65536, size));
>>


-- 
Best regards,
Vladimir