Rework the SCLP boundary check to account for different SCLP commands
(eventually) allowing different boundary sizes.
Move the length check code into a separate function, and introduce a
new function to determine the length of the read SCP data (i.e. the size
from the start of the struct to where the CPU entries should begin).
Signed-off-by: Collin Walling <wall...@linux.ibm.com>
---
hw/s390x/sclp.c | 57 ++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 49 insertions(+), 8 deletions(-)
diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c
index 2bd618515e..987699e3c4 100644
--- a/hw/s390x/sclp.c
+++ b/hw/s390x/sclp.c
@@ -49,6 +49,34 @@ static inline bool sclp_command_code_valid(uint32_t code)
return false;
}
+static bool sccb_has_valid_boundary(uint64_t sccb_addr, uint32_t code,
+ SCCBHeader *header)
+{
+ uint64_t current_len = sccb_addr + be16_to_cpu(header->length);
+ uint64_t allowed_len = (sccb_addr & PAGE_MASK) + PAGE_SIZE;
+
+ switch (code & SCLP_CMD_CODE_MASK) {
+ default:
+ if (current_len <= allowed_len) {
+ return true;
+ }
+ }
+ header->response_code = cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
+ return false;
+}
+
+/* Calculates sufficient SCCB length to store a full Read SCP/CPU response */
+static bool sccb_has_sufficient_len(SCCB *sccb, int num_cpus, int data_len)
+{
+ int required_len = data_len + num_cpus * sizeof(CPUEntry);
+
+ if (be16_to_cpu(sccb->h.length) < required_len) {
+ sccb->h.response_code = cpu_to_be16(SCLP_RC_INSUFFICIENT_SCCB_LENGTH);
+ return false;
+ }
+ return true;
+}
+
static void prepare_cpu_entries(MachineState *ms, CPUEntry *entry, int *count)
{
uint8_t features[SCCB_CPU_FEATURE_LEN] = { 0 };
@@ -66,6 +94,16 @@ static void prepare_cpu_entries(MachineState *ms, CPUEntry
*entry, int *count)
}
}
+/*
+ * The data length denotes the start of the struct to where the first
+ * CPU entry is to be allocated. This value also denotes the offset_cpu
+ * field.
+ */
+static int get_read_scp_info_data_len(void)
+{
+ return offsetof(ReadInfo, entries);
+}
+
/* Provide information about the configuration, CPUs and storage */
static void read_SCP_info(SCLPDevice *sclp, SCCB *sccb)
{
@@ -74,16 +112,16 @@ static void read_SCP_info(SCLPDevice *sclp, SCCB *sccb)
int cpu_count;
int rnsize, rnmax;
IplParameterBlock *ipib = s390_ipl_get_iplb();
+ int data_len = get_read_scp_info_data_len();
- if (be16_to_cpu(sccb->h.length) < (sizeof(ReadInfo) + cpu_count *
sizeof(CPUEntry))) {
- sccb->h.response_code = cpu_to_be16(SCLP_RC_INSUFFICIENT_SCCB_LENGTH);
+ if (!sccb_has_sufficient_len(sccb, machine->possible_cpus->len, data_len))
{
return;
}
/* CPU information */
prepare_cpu_entries(machine, read_info->entries, &cpu_count);
read_info->entries_cpu = cpu_to_be16(cpu_count);
- read_info->offset_cpu = cpu_to_be16(offsetof(ReadInfo, entries));
+ read_info->offset_cpu = cpu_to_be16(data_len);
read_info->highest_cpu = cpu_to_be16(machine->smp.max_cpus - 1);
read_info->ibc_val = cpu_to_be32(s390_get_ibc_val());
@@ -132,16 +170,16 @@ static void sclp_read_cpu_info(SCLPDevice *sclp, SCCB
*sccb)
{
MachineState *machine = MACHINE(qdev_get_machine());
ReadCpuInfo *cpu_info = (ReadCpuInfo *) sccb;
+ int data_len = offsetof(ReadCpuInfo, entries);
int cpu_count;
- if (be16_to_cpu(sccb->h.length) < (sizeof(ReadCpuInfo) + cpu_count *
sizeof(CPUEntry))) {
- sccb->h.response_code = cpu_to_be16(SCLP_RC_INSUFFICIENT_SCCB_LENGTH);
+ if (!sccb_has_sufficient_len(sccb, machine->possible_cpus->len, data_len))
{
return;
}
prepare_cpu_entries(machine, cpu_info->entries, &cpu_count);
cpu_info->nr_configured = cpu_to_be16(cpu_count);
- cpu_info->offset_configured = cpu_to_be16(offsetof(ReadCpuInfo, entries));
+ cpu_info->offset_configured = cpu_to_be16(data_len);
cpu_info->nr_standby = cpu_to_be16(0);
/* The standby offset is 16-byte for each CPU */
@@ -227,6 +265,10 @@ int sclp_service_call_protected(CPUS390XState *env,
uint64_t sccb,
goto out_write;
}
+ if (!sccb_has_valid_boundary(sccb, code, &work_sccb.h)) {
+ goto out_write;
+ }
+
sclp_c->execute(sclp, &work_sccb, code);
out_write:
s390_cpu_pv_mem_write(env_archcpu(env), 0, &work_sccb,
@@ -272,8 +314,7 @@ int sclp_service_call(CPUS390XState *env, uint64_t sccb,
uint32_t code)
goto out_write;
}
- if ((sccb + be16_to_cpu(work_sccb.h.length)) > ((sccb & PAGE_MASK) +
PAGE_SIZE)) {
- work_sccb.h.response_code =
cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
+ if (!sccb_has_valid_boundary(sccb, code, &work_sccb.h)) {
goto out_write;
}
--
2.21.3
