Messages in this thread | | | Date | Wed, 4 Sep 2013 15:57:54 +0200 | From | Olaf Hering <> | Subject | Re: [PATCH 1/1] Drivers: hv: util: Fix a bug in version negotiation code for util services |
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On Tue, Jul 02, K. Y. Srinivasan wrote:
> The current code picked the highest version advertised by the host. WS2012 R2 > has implemented a protocol version for KVP that is not compatible with prior > protocol versions of KVP. Fix the bug in the current code by explicitly specifying > the protocol version that the guest can support.
> -void vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp, > +bool vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp, > struct icmsg_negotiate *negop, u8 *buf, > - int max_fw_version, int max_srv_version) > + int fw_version, int srv_version)
> +fw_error: > + if (!found_match) { > + negop->icframe_vercnt = 0; > + negop->icmsg_vercnt = 0; > + } else { > + negop->icframe_vercnt = 1; > + negop->icmsg_vercnt = 1; > + } > + > + negop->icversion_data[0].major = icframe_major; > + negop->icversion_data[0].minor = icframe_minor; > + negop->icversion_data[1].major = icmsg_major; > + negop->icversion_data[1].minor = icmsg_minor; > + return found_match; > }
The new vmbus_prep_negotiate_resp function modifies the *negop buffer if no match is found. If called twice from hv_kvp_onchannelcallback, the second call uses the modified buffer from the the first call. As a result the matching will fail for both calls. If I leave the buffer alone, kvp works again on ws2008.
I suggest to let callers deal with error handling. Also as a cleanup, vmbus_prep_negotiate_resp does not make use of the negop passed to it. So that arg can be removed.
Olaf
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