From 5097155bdf39bd18a778b985354b0b38fd499f55 Mon Sep 17 00:00:00 2001
From: Chrissie Caulfield <ccaulfie@redhat.com>
Date: Wed, 13 Jan 2021 14:12:02 +0000
Subject: [PATCH] strlcpy: Check for maxlen underflow (#432)

* strlcpy: Check for maxlen underflow

https://github.com/ClusterLabs/libqb/issues/429

* Always terminate the string if maxlen is > 0
---
 lib/strlcpy.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/lib/strlcpy.c b/lib/strlcpy.c
index 4071edf32..63e17f783 100644
--- a/lib/strlcpy.c
+++ b/lib/strlcpy.c
@@ -33,8 +33,12 @@ strlcpy(char *dest, const char * src, size_t maxlen)
 	size_t	srclen = strlen(src);
 	size_t	len2cpy = QB_MIN(maxlen-1, srclen);
 
-	if (len2cpy > 0) {
-		strncpy(dest, src, len2cpy+1);
+	/* check maxlen separately as it could have underflowed from 0 above. */
+	if (maxlen) {
+		if (len2cpy > 0) {
+			strncpy(dest, src, len2cpy+1);
+		}
+		/* Always terminate, even if its empty */
 		dest[len2cpy] = '\0';
 	}
 	return srclen;