Messages in this thread | ![/](/images/icornerl.gif) | | Date | Thu, 19 Jan 2023 10:04:38 +0100 | From | Robert Richter <> | Subject | Re: [PATCH v3] cxl/mbox: Fix Payload Length check for Get Log command |
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On 19.01.23 09:20:53, Robert Richter wrote: > Commit 2aeaf663b85e introduced strict checking for variable length > payload size validation. The payload length of received data must > match the size of the requested data by the caller except for the case > where the min_out value is set. > > The Get Log command does not have a header with a length field set. > The Log size is determined by the Get Supported Logs command (CXL 3.0, > 8.2.9.5.1). However, the actual size can be smaller and the number of > valid bytes in the payload output must be determined reading the > Payload Length field (CXL 3.0, Table 8-36, Note 2). > > Two issues arise: The command can successfully complete with a payload > length of zero. And, the valid payload length must then also be > consumed by the caller. > > Change cxl_xfer_log() to pass the number of payload bytes back to the > caller to determine the number of log entries. Implement the payload > handling as a special case where mbox_cmd->size_out is consulted when > cxl_internal_send_cmd() returns -EIO. A WARN_ONCE() is added to check > that -EIO is only returned in case of an unexpected output size. > > Logs can be bigger than the maximum payload length and multiple Get > Log commands can be issued. If the received payload size is smaller > than the maximum payload size we can assume all valid bytes have been > fetched. Stop sending further Get Log commands then. > > On that occasion, change debug messages to also report the opcodes of > supported commands. > > The variable payload commands GET_LSA and SET_LSA are not affected by > this strict check: SET_LSA cannot be broken because SET_LSA does not > return an output payload, and GET_LSA never expects short reads. > > Fixes: 2aeaf663b85e ("cxl/mbox: Add variable output size validation for internal commands") > Signed-off-by: Robert Richter <rrichter@amd.com> > --- > v3: > * Added comment to the WARN_ONCE(). (Jonathan) > * Passing a size pointer to report the payload size back. (Jonathan) > * Moved logging of supported opcodes out of this patch for a separate > change. (Jonathan)
Please ignore that version, I accidentally sent it out untested. Sorry for that. I will send a v4 instead.
-Robert
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