commit 4075960842c5486f90f25be5837bb0e44f2dbf91
author Kostya Serebryany <kcc@google.com> Wed May 23 23:55:54 2018 +0000
committer Copybara-Service <copybara-worker@google.com> Thu Mar 25 23:17:06 2021 -0700
tree 1968b0445580cb32fefbfa900b317f9fa7c32d66
parent bc9227714f67391468d0562ab43b2ec50945335e

[libFuzzer] fix two off-by-ones (!!) in the data flow tracer

llvm-svn: 333142
GitOrigin-RevId: 500ca8713cff9d6b946593eab4186bcdc74d6367

dataflow/DataFlow.cpp

diff --git a/dataflow/DataFlow.cpp b/dataflow/DataFlow.cpp
index fb7f672..c55c68e 100644
--- a/dataflow/DataFlow.cpp
+++ b/dataflow/DataFlow.cpp
@@ -90,8 +90,9 @@
 }
 
 static void SetBytesForLabel(dfsan_label L, char *Bytes) {
-  if (L <= InputLen) {
-    Bytes[L] = '1';
+  assert(L);
+  if (L <= InputLen + 1) {
+    Bytes[L - 1] = '1';
   } else {
     auto *DLI = dfsan_get_label_info(L);
     SetBytesForLabel(DLI->l1, Bytes);