Fix issue caused by NULL at msg pointer

when malloc() failed to allocate memory for msg buffer.
msg buffer can be NULL. Add a NULL check to return
before passing to snprintf() in wpas_auth_failed() api

Bug: 262328781
Test: STA connect/disconnect
Change-Id: Ic3cf55f5c21d2d955fa665a645674a0127f26528
diff --git a/wpa_supplicant/wpa_supplicant.c b/wpa_supplicant/wpa_supplicant.c
index 17bb231..772067f 100644
--- a/wpa_supplicant/wpa_supplicant.c
+++ b/wpa_supplicant/wpa_supplicant.c
@@ -8367,6 +8367,8 @@
 		ssid->id, wpa_ssid_txt(ssid->ssid, ssid->ssid_len),
 		ssid->auth_failures, dur, reason) + 1;
 	char *msg = os_malloc(msg_len);
+	if (!msg)
+		return;
 	snprintf(msg, msg_len, format_str,
 		ssid->id, wpa_ssid_txt(ssid->ssid, ssid->ssid_len),
 		ssid->auth_failures, dur, reason);