[libvirt] [PATCH 01/11] tlscontext: Make sure to get proper pointer to name

[Osier Yang]

On 2013年02月01日 00:41, Eric Blake wrote:
> On 01/31/2013 03:44 AM, Osier Yang wrote:
>> On 2013年01月31日 03:36, John Ferlan wrote:
>>> The 'dname' string was only filled in within the loop when available;
>>> however, the TRACE macros used it unconditionally and caused Coverity
>>> to compain about BAD_SIZEOF.  Using a dnameptr keeps Coverity at bay and
>
> s/compain/complain/
>
>>> makes sure dname was properly filled before attempting the TRACE message.
>>> ---
>>>    src/rpc/virnettlscontext.c | 8 +++++---
>>>    1 file changed, 5 insertions(+), 3 deletions(-)
>>>
>
>>> @@ -950,6 +950,7 @@ static int
>>> virNetTLSContextValidCertificate(virNetTLSContextPtr ctxt,
>>>        unsigned int nCerts, i;
>>>        char dname[256];
>>>        size_t dnamesize = sizeof(dname);
>>> +    char *dnameptr = NULL;
>
> Would it be any simpler to just 0-initialize dname, as in:
>
> char dname[256] = "";
>
>
>>>
>>>        PROBE(RPC_TLS_CONTEXT_SESSION_ALLOW,
>>>              "ctxt=%p sess=%p dname=%s",
>>> -          ctxt, sess, dname);
>
> At which point, the PROBE(..., dname) would be guaranteed to have a NUL
> terminator within range?  If I understand it, Coverity is complaining
> that if dname is uninitialized, then the PROBE() may read beyond 256
> bytes while looking for the end of a string.
>
>>
>> I guess dname[0] is guaranteed to be not nul as long as
>> gnutls_x509_crt_get_dn succeeded.
>
> Not unless we pre-initialize dname[0].

There is memset in the code actually, if you check the function.

>
>>
>> If so, the patch can be simplified as:
>>
>> dname[0] ? dname : "(unknown)"
>
> Using a conditional would make the difference between a probe stating
> 'dname=' vs. 'dname=(unknown)'; I don't think it adds that much to need
> a ternary ?: in the PROBE.
>