On 09.05.20 01:08, Collin Walling wrote: > The header of the SCCB contains the actual length of the > SCCB. Instead of using a static 4K size, let's allow > for a variable size determined by the value set 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/sclp.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c > index 470d5da7a2..748d04a0e2 100644 > --- a/hw/s390x/sclp.c > +++ b/hw/s390x/sclp.c > @@ -244,15 +244,16 @@ 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); > > - s390_cpu_pv_mem_read(env_archcpu(env), 0, &work_sccb, sccb_len); > + s390_cpu_pv_mem_read(env_archcpu(env), 0, &work_sccb, > sizeof(SCCBHeader)); > > if (!sclp_command_code_valid(code)) { > work_sccb.h.response_code = > cpu_to_be16(SCLP_RC_INVALID_SCLP_COMMAND); > goto out_write; > } > > + s390_cpu_pv_mem_read(env_archcpu(env), 0, &work_sccb, > work_sccb.h.length);
be16_to_cpu() necessary. > + > if (!check_sccb_boundary_valid(sccb, code, &work_sccb)) { > goto out_write; > } > @@ -271,8 +272,6 @@ int sclp_service_call(CPUS390XState *env, uint64_t sccb, > uint32_t code) > SCLPDeviceClass *sclp_c = SCLP_GET_CLASS(sclp); > SCCB work_sccb; > > - hwaddr sccb_len = sizeof(SCCB); > - > /* first some basic checks on program checks */ > if (env->psw.mask & PSW_MASK_PSTATE) { > return -PGM_PRIVILEGED; > @@ -290,13 +289,16 @@ int sclp_service_call(CPUS390XState *env, uint64_t > sccb, uint32_t code) > * from playing dirty tricks by modifying the memory content after > * the host has checked the values > */ > - cpu_physical_memory_read(sccb, &work_sccb, sccb_len); > + cpu_physical_memory_read(sccb, &work_sccb, sizeof(SCCBHeader)); > > /* Valid sccb sizes */ > if (be16_to_cpu(work_sccb.h.length) < sizeof(SCCBHeader)) { > return -PGM_SPECIFICATION; > } > > + /* the header contains the actual length of the sccb */ > + cpu_physical_memory_read(sccb, &work_sccb, work_sccb.h.length); be16_to_cpu() necessary. > + > if (!sclp_command_code_valid(code)) { > work_sccb.h.response_code = > cpu_to_be16(SCLP_RC_INVALID_SCLP_COMMAND); > goto out_write; > -- Thanks, David / dhildenb