From: Mark Andrews <marka@isc.org>
Date: Tue, 3 Jan 2023 03:28:11 +0000 (+1100)
Subject: Do not pass NULL pointer to memmove - undefined behaviour
X-Git-Tag: v9.19.9~52^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=096b280b1c5a19f2a613682f421543d665ed6c4c;p=thirdparty%2Fbind9.git

Do not pass NULL pointer to memmove - undefined behaviour

Check if 'old_base' is NULL and if so skip calling memmove.
---

diff --git a/lib/isc/include/isc/buffer.h b/lib/isc/include/isc/buffer.h
index d9cec44c6b0..4e73c9c7c57 100644
--- a/lib/isc/include/isc/buffer.h
+++ b/lib/isc/include/isc/buffer.h
@@ -1150,7 +1150,9 @@ isc_buffer_reserve(isc_buffer_t *restrict dbuf, const unsigned int size) {
 	if (!dbuf->dynamic) {
 		void *old_base = dbuf->base;
 		dbuf->base = isc_mem_get(dbuf->mctx, len);
-		memmove(dbuf->base, old_base, dbuf->used);
+		if (old_base != NULL) {
+			memmove(dbuf->base, old_base, dbuf->used);
+		}
 		dbuf->dynamic = true;
 	} else {
 		dbuf->base = isc_mem_reget(dbuf->mctx, dbuf->base, dbuf->length,