[libvirt] [PATCH] rpc: Correct the wrong payload size checking

[Osier Yang]

On 14/10/13 21:26, Daniel P. Berrange wrote:
> On Mon, Oct 14, 2013 at 03:22:27PM +0800, Osier Yang wrote:
>> <...>
>> /* Size of message length field. Not counted in VIR_NET_MESSAGE_MAX
>>   * and VIR_NET_MESSAGE_INITIAL.
>>   */
>> const VIR_NET_MESSAGE_LEN_MAX = 4;
>> </...>
>>
>> However, msg->bufferLength includes the length word. The wrong checking
>> was introduced by commit e914dcfd.
>>
>> * src/rpc/virnetmessage.c:
>>    - Correct the checking in virNetMessageEncodePayloadRaw
>>    - Use a new variable to track the new payload length in
>>      virNetMessageEncodePayloadRaw
>> ---
>>   src/rpc/virnetmessage.c | 19 +++++++++++++------
>>   1 file changed, 13 insertions(+), 6 deletions(-)
>>
>> diff --git a/src/rpc/virnetmessage.c b/src/rpc/virnetmessage.c
>> index 8f4e4bc..4c60424 100644
>> --- a/src/rpc/virnetmessage.c
>> +++ b/src/rpc/virnetmessage.c
>> @@ -346,15 +346,17 @@ int virNetMessageEncodePayload(virNetMessagePtr msg,
>>   
>>       /* Try to encode the payload. If the buffer is too small increase it. */
>>       while (!(*filter)(&xdr, data)) {
>> -        if ((msg->bufferLength - VIR_NET_MESSAGE_LEN_MAX) * 4 > VIR_NET_MESSAGE_MAX) {
>> +        unsigned int newlen = (msg->bufferLength - VIR_NET_MESSAGE_LEN_MAX) * 4 +
>> +            VIR_NET_MESSAGE_LEN_MAX;
>> +
>> +        if (newlen > VIR_NET_MESSAGE_MAX + VIR_NET_MESSAGE_LEN_MAX) {
> You've not actually changed the logic here at all - you've just
> added VIR_NET_MESSAGE_LEN_MAX to both sides of the '>'. So this
> change is a no-op. Please drop it.

Yes, the logic is not changed, but I wanted to calculate the new buffer 
length
once instead of twice, and it's more readable for the code. So I'd like 
keep it.

>
>
>>               virReportError(VIR_ERR_RPC, "%s", _("Unable to encode message payload"));
>>               goto error;
>>           }
>>   
>>           xdr_destroy(&xdr);
>>   
>> -        msg->bufferLength = (msg->bufferLength - VIR_NET_MESSAGE_LEN_MAX) * 4 +
>> -            VIR_NET_MESSAGE_LEN_MAX;
>> +        msg->bufferLength = newlen;
> Again, nothing changed. Drop this.
>
>>   
>>           if (VIR_REALLOC_N(msg->buffer, msg->bufferLength) < 0)
>>               goto error;
>> @@ -426,10 +428,15 @@ int virNetMessageEncodePayloadRaw(virNetMessagePtr msg,
>>   
>>       /* If the message buffer is too small for the payload increase it accordingly. */
>>       if ((msg->bufferLength - msg->bufferOffset) < len) {
>> -        if ((msg->bufferOffset + len) > VIR_NET_MESSAGE_MAX) {
>> +        if ((msg->bufferOffset + len) >
>> +            VIR_NET_MESSAGE_MAX + VIR_NET_MESSAGE_LEN_MAX) {
> Bracket both sides of the '>' for clarity, not just the left-hand-side.
>

So except this, Can I get an ACK?


-------------- next part --------------
diff --git a/src/rpc/virnetmessage.c b/src/rpc/virnetmessage.c
index 4c60424..79a50f6 100644
--- a/src/rpc/virnetmessage.c
+++ b/src/rpc/virnetmessage.c
@@ -429,7 +429,7 @@ int virNetMessageEncodePayloadRaw(virNetMessagePtr msg,
     /* If the message buffer is too small for the payload increase it accordingly. */
     if ((msg->bufferLength - msg->bufferOffset) < len) {
         if ((msg->bufferOffset + len) >
-            VIR_NET_MESSAGE_MAX + VIR_NET_MESSAGE_LEN_MAX) {
+            (VIR_NET_MESSAGE_MAX + VIR_NET_MESSAGE_LEN_MAX)) {
             virReportError(VIR_ERR_RPC,
                            _("Stream data too long to send "
                              "(%zu bytes needed, %zu bytes available)"),