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
---
hw/s390x/event-facility.c | 2 +-
hw/s390x/sclp.c | 55 ++-
include/hw/s390x/sclp.h | 2 +-
3 files changed, 33 insertions(+), 26 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 a37cfbf534..4ae6fb400b 100644
--- a/hw/s390x/sclp.c
+++ b/hw/s390x/sclp.c
@@ -231,25 +231,29 @@ 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;
+g_autofree SCCB *work_sccb = NULL;
-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(be16_to_cpu(header.length));
+s390_cpu_pv_mem_read(env_archcpu(env), 0, work_sccb,
+ be16_to_cpu(header.length));
if (!sclp_command_code_valid(code)) {
-work_sccb.h.response_code = cpu_to_be16(SCLP_RC_INVALID_SCLP_COMMAND);
+work_sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_SCLP_COMMAND);
goto out_write;
}
-if (!sccb_verify_boundary(sccb, be16_to_cpu(work_sccb.h.length))) {
-work_sccb.h.response_code =
cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
+if (!sccb_verify_boundary(sccb, be16_to_cpu(work_sccb->h.length))) {
+work_sccb->h.response_code =
cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
goto out_write;
}
-sclp_c->execute(sclp, &work_sccb, code);
+sclp_c->execute(sclp, work_sccb, code);
out_write:
-s390_cpu_pv_mem_write(env_archcpu(env), 0, &work_sccb,
- be16_to_cpu(work_sccb.h.length));
+s390_cpu_pv_mem_write(env_archcpu(env), 0, work_sccb,
+ be16_to_cpu(work_sccb->h.length));
sclp_c->service_interrupt(sclp, SCLP_PV_DUMMY_ADDR);
return 0;
}
@@ -258,9 +262,8 @@ int sclp_service_call(CPUS390XState *env, uint64_t sccb,
uint32_t code)
{
SCLPDevice *sclp = get_sclp_device();
SCLPDeviceClass *sclp_c = SCLP_GET_CLASS(sclp);
-SCCB work_sccb;
-
-hwaddr sccb_len = sizeof(SCCB);
+SCCBHeader header;
+g_autofree SCCB *work_sccb = NULL;
/* first some basic checks on program checks */
if (env->psw.mask & PSW_MASK_PSTATE) {
@@ -274,32 +277,36 @@ int sclp_service_call(CPUS390XState *env, uint64_t sccb,
uint32_t code)
return -PGM_SPECIFICATION;
}
+/* the header contains the actual length of the sccb */
+cpu_physical_memory_read(sccb, &header, sizeof(SCCBHeader));
+
+/* Valid sccb sizes */
+if (be16_to_cpu(header.length) < sizeof(SCCBHeader)) {
+return -PGM_SPECIFICATION;
+}
+
/*
* we want to work on a private copy of the sccb, to prevent guests
* 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);
-
-/* Valid sccb sizes */
-if (be16_to_cpu(work_sccb.h.length) < sizeof(SCCBHeader)) {
-return -PGM_SPECIFICATION;
-}
+work_sccb = g_malloc0(be16_to_cpu(header.length));
+cpu_physical_memory_read(sccb, work_sccb, be16_to_cpu(header.length));
if (!sclp_command_code_valid(code)) {
-work_sccb.h.response_code = cpu_to_be16(SCLP_RC_INVALID_SCLP_COMMAND);
+work_sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_SCLP_COMMAND);
goto out_write;
}
-if (!sccb_verify_boundary(sccb, be16_to_cpu(work_sccb.h.length))) {
-work_sccb.h.response_code =
cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
+if (!sccb_verify_boundary(sccb, be16_to_cpu(work_sccb->h.length))) {
+work_sccb->h.response_code =
cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
goto out_write;
}
-sclp_c->execute(sclp, &work_sccb, code);
+sclp_c->execute(sclp, work_sccb, code);
out_write:
-cpu_physical_memory_write(sccb, &work_sccb,
- be16_to_cpu(work_sccb.h.length));
+
