From 1ee3028a58e7c4a78491dd07a97feaecbdf5731f Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Mon, 9 Jan 2023 12:52:22 +1030
Subject: [PATCH] stringbuilder: avoid overwriting end of buffer with nul
 terminator.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 ccan/stringbuilder/stringbuilder.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/ccan/stringbuilder/stringbuilder.c b/ccan/stringbuilder/stringbuilder.c
index d34de811..8eb4ab42 100644
--- a/ccan/stringbuilder/stringbuilder.c
+++ b/ccan/stringbuilder/stringbuilder.c
@@ -22,7 +22,8 @@ static int stringbuilder_cpy(
 	if (*str != s) {
 		if (!s_len)
 			s_len = strlen(s);
-		if (s_len > *str_sz)
+		/* Include nul term! */
+		if (s_len >= *str_sz)
 			return EMSGSIZE;
 		strcpy(*str, s);
 	}
-- 
2.39.2