[S390] call home: fix string length handling

After copying uts->nodename to the static nodename array the static
version isn't necessarily zero termininated, since the size of the
array is one byte too short.
Afterwards doing strncat(data, nodename, strlen(nodename)); may copy
an arbitrary large amount of bytes.
Fix this by getting rid of the static array and using strncat with
proper length limit.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 6 insertions, 8 deletions

diff --git a/drivers/s390/char/sclp_async.c b/drivers/s390/char/sclp_async.c
index 3c20aa131180..b44462a6c6d3 100644
--- a/drivers/s390/char/sclp_async.c
+++ b/drivers/s390/char/sclp_async.c
@@ -26,7 +26,6 @@ static struct sclp_async_sccb *sccb;
 static int sclp_async_send_wait(char *message);
 static struct ctl_table_header *callhome_sysctl_header;
 static DEFINE_SPINLOCK(sclp_async_lock);
-static char nodename[64];
 #define SCLP_NORMAL_WRITE       0x00
 
 struct async_evbuf {
@@ -52,9 +51,10 @@ static struct sclp_register sclp_async_register = {
 static int call_home_on_panic(struct notifier_block *self,
                               unsigned long event, void *data)
 {
-                strncat(data, nodename, strlen(nodename));
-                sclp_async_send_wait(data);
-                return NOTIFY_DONE;
+        strncat(data, init_utsname()->nodename,
+                sizeof(init_utsname()->nodename));
+        sclp_async_send_wait(data);
+        return NOTIFY_DONE;
 }
 
 static struct notifier_block call_home_panic_nb = {
@@ -183,10 +183,8 @@ static int __init sclp_async_init(void)
                 goto out_mem;
         rc = atomic_notifier_chain_register(&panic_notifier_list,
                                             &call_home_panic_nb);
-        if (rc)
-                goto out_mem;
-        strncpy(nodename, init_utsname()->nodename, 64);
-        goto out;
+        if (!rc)
+                goto out;
 out_mem:
         kfree(request);
         free_page((unsigned long) sccb);