commit eca592264c4b08d409b6370df1e672e78fb41c37
author Than McIntosh <thanm@google.com> Fri Aug 05 08:16:17 2022 -0400
committer Copybara-Service <copybara-worker@google.com> Fri Aug 05 08:40:54 2022 -0700
tree 2fd630bcd11b90e1775be59c388721ec3ba19bea
parent 95807154b1593300ea6c165f58154429e710e2f7

tsan: fix bug in shadow reset introduced in D128909

Correct a bug in the code that resets shadow memory introduced as part
of a previous change for the Go race detector (D128909). The bug was
that only the most recently added shadow segment was being reset, as
opposed to the entire extent of the segment created so far. This
fixes a bug identified in Google internal testing (b/240733951).

Differential Revision: https://reviews.llvm.org/D131256

GitOrigin-RevId: 24a62bfe9a497bb494aae24e33f4d8349720a9c8

lib/tsan/rtl/tsan_rtl.cpp

diff --git a/lib/tsan/rtl/tsan_rtl.cpp b/lib/tsan/rtl/tsan_rtl.cpp
index ff3bb33..db3d945 100644
--- a/lib/tsan/rtl/tsan_rtl.cpp
+++ b/lib/tsan/rtl/tsan_rtl.cpp
@@ -603,8 +603,8 @@
     // Second and subsequent calls map heap.
     if (shadow_end <= ctx->mapped_shadow_end)
       return;
-    if (ctx->mapped_shadow_begin < shadow_begin)
-      ctx->mapped_shadow_begin = shadow_begin;
+    if (!ctx->mapped_shadow_begin || ctx->mapped_shadow_begin > shadow_begin)
+       ctx->mapped_shadow_begin = shadow_begin;
     if (shadow_begin < ctx->mapped_shadow_end)
       shadow_begin = ctx->mapped_shadow_end;
     VPrintf(2, "MapShadow begin/end = (0x%zx-0x%zx)\n",