On 11/09/2020 20.16, Collin Walling wrote: > On 9/10/20 1:56 PM, Collin Walling wrote: >> On 9/10/20 1:50 PM, Thomas Huth wrote: >>> On 10/09/2020 11.36, Collin Walling wrote: >>>> The header contained within the SCCB passed to the SCLP service call >>>> contains the actual length of the SCCB. Instead of allocating a static >>>> 4K size for the work sccb, let's allow for a variable size determined >>>> by the value in the header. The proper checks are already in place to >>>> ensure the SCCB length is sufficent to store a full response and that >>>> the length does not cross any explicitly-set boundaries. >>>> >>>> Signed-off-by: Collin Walling <wall...@linux.ibm.com> >>>> --- >>>> hw/s390x/event-facility.c | 2 +- >>>> hw/s390x/sclp.c | 58 ++++++++++++++++++++++----------------- >>>> include/hw/s390x/sclp.h | 2 +- >>>> 3 files changed, 35 insertions(+), 27 deletions(-) >>>> >>>> diff --git a/hw/s390x/event-facility.c b/hw/s390x/event-facility.c >>>> index 645b4080c5..ed92ce510d 100644 >>>> --- a/hw/s390x/event-facility.c >>>> +++ b/hw/s390x/event-facility.c >>>> @@ -213,7 +213,7 @@ static uint16_t >>>> handle_sccb_read_events(SCLPEventFacility *ef, SCCB *sccb, >>>> >>>> event_buf = &red->ebh; >>>> event_buf->length = 0; >>>> - slen = sizeof(sccb->data); >>>> + slen = sccb_data_len(sccb); >>>> >>>> rc = SCLP_RC_NO_EVENT_BUFFERS_STORED; >>>> >>>> diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c >>>> index 69a8724dc7..cb8e2e8ec3 100644 >>>> --- a/hw/s390x/sclp.c >>>> +++ b/hw/s390x/sclp.c >>>> @@ -231,25 +231,30 @@ int sclp_service_call_protected(CPUS390XState *env, >>>> uint64_t sccb, >>>> { >>>> SCLPDevice *sclp = get_sclp_device(); >>>> SCLPDeviceClass *sclp_c = SCLP_GET_CLASS(sclp); >>>> - SCCB work_sccb; >>>> - hwaddr sccb_len = sizeof(SCCB); >>>> + SCCBHeader header; >>>> + SCCB *work_sccb; >>> >>> I'd maybe use "g_autofree SCCB *work_sccb = NULL" so you don't have to >>> worry about doing the g_free() later. >> >> Can do. >> >>> >>>> - s390_cpu_pv_mem_read(env_archcpu(env), 0, &work_sccb, sccb_len); >>>> + s390_cpu_pv_mem_read(env_archcpu(env), 0, &header, >>>> sizeof(SCCBHeader)); >>>> + >>>> + work_sccb = g_malloc0(header.length); >>> >>> Please use be16_to_cpu(header.length) here as well. >> >> Good catch, thanks! >> > > Shouldn't the mallocs use cpu_to_be16 instead since the header length > was read in from a cpu?
Now you confuse me ... s390x is big endian, so to get a usable value, we have to convert big-endian to the host byte order, not the other way round, don't we? Thomas