[compiler-rt] [tsan] Change personality CHECK to Printf() + Die() (PR #142821)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: Thurston Dang (thurstond)

<details>
<summary>Changes</summary>

Currently, if TSan needs to disable ASLR but is unable to do so, it aborts with a cryptic message:
```
    ThreadSanitizer: CHECK failed: tsan_platform_linux.cpp:290 "((personality(old_personality | ADDR_NO_RANDOMIZE))) != ((-1))"
```
and a segfault (https://github.com/google/sanitizers/issues/837#issuecomment-2939267531).

This patch replaces the CHECK with more user-friendly diagnostics and suggestions via printf, followed by Die().

---
Full diff: https://github.com/llvm/llvm-project/pull/142821.diff


1 Files Affected:

- (modified) compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp (+21-2) 


``````````diff
diff --git a/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp b/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp
index 373acd3d95d01..469525ac41cf8 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp
@@ -259,7 +259,15 @@ static void ReExecIfNeeded(bool ignore_heap) {
             "WARNING: Program is run with randomized virtual address "
             "space, which wouldn't work with ThreadSanitizer on Android.\n"
             "Re-execing with fixed virtual address space.\n");
-    CHECK_NE(personality(old_personality | ADDR_NO_RANDOMIZE), -1);
+
+    if (personality(old_personality | ADDR_NO_RANDOMIZE) == -1) {
+      Printf(
+          "FATAL: ThreadSanitizer: unable to disable ASLR (perhaps "
+          "sandboxing is enabled?).\n");
+      Printf("FATAL: Please rerun without sandboxing and/or ASLR.\n");
+      Die();
+    }
+
     reexec = true;
   }
 #      endif
@@ -287,7 +295,18 @@ static void ReExecIfNeeded(bool ignore_heap) {
               "possibly due to high-entropy ASLR.\n"
               "Re-execing with fixed virtual address space.\n"
               "N.B. reducing ASLR entropy is preferable.\n");
-      CHECK_NE(personality(old_personality | ADDR_NO_RANDOMIZE), -1);
+
+      if (personality(old_personality | ADDR_NO_RANDOMIZE) == -1) {
+        Printf(
+            "FATAL: ThreadSanitizer: encountered an incompatible memory "
+            "but was unable to disable ASLR (perhaps sandboxing is "
+            "enabled?).\n");
+        Printf(
+            "FATAL: Please rerun with lower ASLR entropy, ASLR disabled, "
+            "and/or sandboxing disabled.\n");
+        Die();
+      }
+
       reexec = true;
     } else {
       Printf(

``````````

</details>


https://github.com/llvm/llvm-project/pull/142821