From d0f52bdb98c8c136784cedb78f20101899eea802 Mon Sep 17 00:00:00 2001
From: djm <djm@openbsd.org>
Date: Wed, 30 Mar 2022 04:27:51 +0000
Subject: [PATCH] avoid NULL deref via ssh-keygen -Y find-principals. bz3409,
 reported by Mateusz Adamowski

---
 usr.bin/ssh/sshsig.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/usr.bin/ssh/sshsig.c b/usr.bin/ssh/sshsig.c
index 8c64b99c0f6..56cd59a3373 100644
--- a/usr.bin/ssh/sshsig.c
+++ b/usr.bin/ssh/sshsig.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshsig.c,v 1.28 2022/02/01 23:34:47 djm Exp $ */
+/* $OpenBSD: sshsig.c,v 1.29 2022/03/30 04:27:51 djm Exp $ */
 /*
  * Copyright (c) 2019 Google LLC
  *
@@ -737,7 +737,7 @@ parse_principals_key_and_options(const char *path, u_long linenum, char *line,
 		return SSH_ERR_KEY_NOT_FOUND; /* blank or all-comment line */
 
 	/* format: identity[,identity...] [option[,option...]] key */
-	if ((tmp = strdelimw(&cp)) == NULL) {
+	if ((tmp = strdelimw(&cp)) == NULL || cp == NULL) {
 		error("%s:%lu: invalid line", path, linenum);
 		r = SSH_ERR_INVALID_FORMAT;
 		goto out;
@@ -775,6 +775,11 @@ parse_principals_key_and_options(const char *path, u_long linenum, char *line,
 			r = SSH_ERR_INVALID_FORMAT;
 			goto out;
 		}
+		if (cp == NULL || *cp == '\0') {
+			error("%s:%lu: missing key", path, linenum);
+			r = SSH_ERR_INVALID_FORMAT;
+			goto out;
+		}
 		*cp++ = '\0';
 		skip_space(&cp);
 		if (sshkey_read(key, &cp) != 0) {
-- 
2.20.1