From: Christian Borntraeger <[email protected]> If a guest submits an sccb with a tiny header length but a large number of event mask entries, the write_event_mask handler will 1. return the wrong RC (ok instead of error) 2. write to memory after the allocated sccb in qemu host memory.
Add the necessary checks. Cc: [email protected] Reviewed-by: Hendrik Brueckner <[email protected]> Reviewed-by: Matthew Rosato <[email protected]> Reviewed-by: Eric Farman <[email protected]> Reviewed-by: Philippe Mathieu-Daudé <[email protected]> Signed-off-by: Christian Borntraeger <[email protected]> Message-ID: <[email protected]> Signed-off-by: Cornelia Huck <[email protected]> (cherry picked from commit d88cd8f5570f4d6e08d62e098a8b7f53cdc75536) Signed-off-by: Michael Tokarev <[email protected]> diff --git a/hw/s390x/event-facility.c b/hw/s390x/event-facility.c index 2b0332c20e2..18361a3bf45 100644 --- a/hw/s390x/event-facility.c +++ b/hw/s390x/event-facility.c @@ -291,6 +291,7 @@ static void read_event_data(SCLPEventFacility *ef, SCCB *sccb) static void write_event_mask(SCLPEventFacility *ef, SCCB *sccb) { WriteEventMask *we_mask = (WriteEventMask *) sccb; + uint16_t sccb_length = be16_to_cpu(sccb->h.length); uint16_t mask_length = be16_to_cpu(we_mask->mask_length); sccb_mask_t tmp_mask; @@ -300,6 +301,11 @@ static void write_event_mask(SCLPEventFacility *ef, SCCB *sccb) return; } + if (sccb_length < sizeof(WriteEventMask) + 4 * mask_length) { + sccb->h.response_code = cpu_to_be16(SCLP_RC_INSUFFICIENT_SCCB_LENGTH); + return; + } + /* * Note: We currently only support masks up to 8 byte length; * the remainder is filled up with zeroes. Older Linux -- 2.47.3
