Most of the option vector helpers have assertions to check their
arguments aren't null. The guest can provide an arbitrary address
for the CAS structure that would result in such null arguments.
Fail CAS with H_PARAMETER and print a warning instead of aborting
QEMU.

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
v2: - print warnings
---
 hw/ppc/spapr_hcall.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index 84e1612595bb..90d74076b09c 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -1701,9 +1701,21 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu,
 
     /* For the future use: here @ov_table points to the first option vector */
     ov_table = addr;
+    if (!ov_table) {
+        warn_report("guest passed an invalid option vector table address");
+        return H_PARAMETER;
+    }
 
     ov1_guest = spapr_ovec_parse_vector(ov_table, 1);
+    if (!ov1_guest) {
+        warn_report("guest didn't provide option vector 1");
+        return H_PARAMETER;
+    }
     ov5_guest = spapr_ovec_parse_vector(ov_table, 5);
+    if (!ov5_guest) {
+        warn_report("guest didn't provide option vector 5");
+        return H_PARAMETER;
+    }
     if (spapr_ovec_test(ov5_guest, OV5_MMU_BOTH)) {
         error_report("guest requested hash and radix MMU, which is invalid.");
         exit(EXIT_FAILURE);