[RHEL7 qemu-kvm PATCH 2/3] s390x: Fix vm name copy length

[mrezanin@redhat.com]

From: Miroslav Rezanina <mrezanin@redhat.com>

There are two cases when vm name is copied but closing \0 can be lost
in case name is too long (>=256 characters).

Updating length to copy so there is space for closing \0.

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 target/s390x/kvm.c         | 2 +-
 target/s390x/misc_helper.c | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
index b8385e6b95..2313b5727e 100644
--- a/target/s390x/kvm.c
+++ b/target/s390x/kvm.c
@@ -1918,7 +1918,7 @@ static void insert_stsi_3_2_2(S390CPU *cpu, __u64 addr, uint8_t ar)
      */
     if (qemu_name) {
         strncpy((char *)sysib.ext_names[0], qemu_name,
-                sizeof(sysib.ext_names[0]));
+                sizeof(sysib.ext_names[0]) - 1);
     } else {
         strcpy((char *)sysib.ext_names[0], "KVMguest");
     }
diff --git a/target/s390x/misc_helper.c b/target/s390x/misc_helper.c
index 58dbc023eb..7c478b9e58 100644
--- a/target/s390x/misc_helper.c
+++ b/target/s390x/misc_helper.c
@@ -369,8 +369,10 @@ uint32_t HELPER(stsi)(CPUS390XState *env, uint64_t a0, uint64_t r0, uint64_t r1)
                 ebcdic_put(sysib.sysib_322.vm[0].name, qemu_name,
                            MIN(sizeof(sysib.sysib_322.vm[0].name),
                                strlen(qemu_name)));
+		memset((char *)sysib.sysib_322.ext_names[0], 0, 
+		       sizeof(sysib.sysib_322.ext_names[0]));
                 strncpy((char *)sysib.sysib_322.ext_names[0], qemu_name,
-                        sizeof(sysib.sysib_322.ext_names[0]));
+                        sizeof(sysib.sysib_322.ext_names[0]) - 1);
             } else {
                 ebcdic_put(sysib.sysib_322.vm[0].name, "TCGguest", 8);
                 strcpy((char *)sysib.sysib_322.ext_names[0], "TCGguest");
-- 
2.18.4