#
# This is to fix a keyboard-interactive authentication brute force
# vulnerability (MaxAuthTries bypass). A CVE number (CVE-2015-5600) has been
# reserved for this problem, but not officially issued yet. This fix came from
# OpenSSH upstream, which will be included in the future OpenSSH 7.0p1 release.
# When we upgrade OpenSSH to 7.0 in the future, we will remove this patch.
#
--- a/auth2-chall.c	Mon Aug  3 15:25:43 2015
+++ b/auth2-chall.c	Mon Aug  3 15:28:17 2015
@@ -82,6 +82,7 @@
 	void *ctxt;
 	KbdintDevice *device;
 	u_int nreq;
+	u_int devices_done;
 };
 
 #ifdef USE_PAM
@@ -168,11 +169,15 @@
 		if (len == 0)
 			break;
 		for (i = 0; devices[i]; i++) {
-			if (!auth2_method_allowed(authctxt,
+			if ((kbdintctxt->devices_done & (1 << i)) != 0 ||
+			    !auth2_method_allowed(authctxt,
 			    "keyboard-interactive", devices[i]->name))
 				continue;
-			if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0)
+			if (strncmp(kbdintctxt->devices, devices[i]->name,
+			    len) == 0) {
 				kbdintctxt->device = devices[i];
+				kbdintctxt->devices_done |= 1 << i;
+			}
 		}
 		t = kbdintctxt->devices;
 		kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL;