From b223f11b2163a80c30084b14cec8dabe944740f5 Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Thu, 17 Sep 2020 15:34:03 -0700
Subject: [PATCH] ubsan: make pointer overflow recoverable

the way `base` is used must allow 2-complement address overflow.
`base` is effectively a virtual pointer, never dereferenced directly.
What matters is `base + index`.
This is the address that will be dereference and must be valid (it is properly validated).
---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index ef1fd2e..6bf952c 100644
--- a/Makefile
+++ b/Makefile
@@ -143,7 +143,7 @@ clangtest-native: clean
 	@CFLAGS="-O3 -Werror -Wconversion -Wno-sign-conversion" $(MAKE) -C $(TESTDIR) native CC=clang
 
 usan: clean
-	CC=clang CFLAGS="-O3 -g -fsanitize=undefined -fno-sanitize-recover=undefined" $(MAKE) test FUZZER_TIME="-T30s" NB_LOOPS=-i1
+	CC=clang CFLAGS="-O3 -g -fsanitize=undefined -fno-sanitize-recover=undefined -fsanitize-recover=pointer-overflow" $(MAKE) test FUZZER_TIME="-T30s" NB_LOOPS=-i1
 
 usan32: clean
 	CFLAGS="-m32 -O3 -g -fsanitize=undefined" $(MAKE) test FUZZER_TIME="-T30s" NB_LOOPS=-i1