From 9c170b3d52bf8e7ca3c14e6788330e79329fcf0b Mon Sep 17 00:00:00 2001
From: Kyle Evans <kevans@FreeBSD.org>
Date: Sat, 4 Nov 2023 21:08:36 -0500
Subject: [PATCH] grep: don't rely on implementation-defined malloc(0) behavior

The very few places that rely on malloc/calloc of a zero-size region
won't attempt to dereference it, so just return NULL rather than rolling
the dice with the underlying malloc implementation.

Reported by:	brooks, Shawn Webb

(cherry picked from commit e116e040f3091eca914a06dcd0bdd9f1aea23add)
---
 usr.bin/grep/util.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/usr.bin/grep/util.c b/usr.bin/grep/util.c
index 68bfd504279e..e3cf6e3cb4d8 100644
--- a/usr.bin/grep/util.c
+++ b/usr.bin/grep/util.c
@@ -650,6 +650,8 @@ grep_malloc(size_t size)
 {
 	void *ptr;
 
+	if (size == 0)
+		return (NULL);
 	if ((ptr = malloc(size)) == NULL)
 		err(2, "malloc");
 	return (ptr);
@@ -663,6 +665,8 @@ grep_calloc(size_t nmemb, size_t size)
 {
 	void *ptr;
 
+	if (nmemb == 0 || size == 0)
+		return (NULL);
 	if ((ptr = calloc(nmemb, size)) == NULL)
 		err(2, "calloc");
 	return (ptr);