Re: [Qemu-devel] [PATCH v4] inet_listen_opts: add error checking

[Eric Blake]

On 12/13/2013 05:42 AM, Eric Blake wrote:
> On 12/13/2013 03:12 AM, Gerd Hoffmann wrote:
>> Don't use atoi() function which doesn't detect errors, switch to
>> strtol and error out on failures.  Also add a range check while
>> being at it.
>>
>> [ v4: didn't commit buildfix.  -ENOCOFFEE.  sorry for the spam ]
>> [ v3: oops, v2 didn't build ]
>> [ v2: use parse_uint_full instead of strtol ]
> 

> 
>> +    if (port_offset) {
>> +        unsigned long long baseport;
>> +        if (parse_uint_full(port, &baseport, 10) < 0) {
>> +            error_setg(errp, "can't convert to a number: %s", port);
>> +            return -1;
>> +        }
>> +        if (baseport + port_offset > 65535) {
>> +            error_setg(errp, "port %s out of range", port);
> 
> error_setg() is still reporting on a bogus errno value at this point.

My bad, now it's my turn for early-morning confusion.

I was thinking of error_setg_errno, but you are using error_setg.

That said, you STILL have a problem:

> +        if (baseport + port_offset > 65535) {

If baseport is 0xfffffffffffffffe, and port_offset is 5000, then their
sum is 4998 which is not > 65535, so you fall through:

> +            error_setg(errp, "port %s out of range", port);
> +            return -1;
> +        }
> +        snprintf(port, sizeof(port), "%d", (int)baseport + port_offset);

and happily use a value that is less than port_offset at this point.  I
don't think you meant to do that.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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