[sanitizer] Disallow external_symbolizer_path with AT_SECURE

[fmayer]

See google/sanitizers#1130.

[llvmbot]

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

Author: Florian Mayer (fmayer)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/92611.diff

1 Files Affected:

• (modified) compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp (+8-1)

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp
index 0ddc24802d216..68d51dd1cb9b7 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp
@@ -25,6 +25,7 @@
 #  include "sanitizer_common.h"
 #  include "sanitizer_file.h"
 #  include "sanitizer_flags.h"
+#  include "sanitizer_getauxval.h"
 #  include "sanitizer_internal_defs.h"
 #  include "sanitizer_linux.h"
 #  include "sanitizer_placement_new.h"
@@ -408,7 +409,13 @@ const char *Symbolizer::PlatformDemangle(const char *name) {
 
 static SymbolizerTool *ChooseExternalSymbolizer(LowLevelAllocator *allocator) {
   const char *path = common_flags()->external_symbolizer_path;
-
+  // This is so we can use the weak definition from sanitizer_getauxval.h
+  if (&getauxval && getauxval(/* AT_SECURE */ 23) != 0) {
+    Report(
+        "ERROR: external_symbolizer_path cannot be used for AT_SECURE "
+        "(e.g. setuid binaries).\n");
+    Die();
+  }
   if (path && internal_strchr(path, '%')) {
     char *new_path = (char *)InternalAlloc(kMaxPathLength);
     SubstituteForFlagValue(path, new_path, kMaxPathLength);

[fmayer]

@bigb4ng FYI

[fmayer]

@fmayer Cool. Friendly reminders:

1. SANITIZER_GO is currently not affected by this patch due to

   llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_getauxval.h

   Line 26 in e2db08f

   !SANITIZER_GO

If ran on a system that has getauxval, it will also work for SANITIZER_GO, because of the weak declaration in the #else.

2. log_path=stdout and log_path=stderr for AT_SECURE are not supported in this version.

This is about external_symbolizer_path :)

Trust your judgement on those. I will close #92593.

Wait, this addresses a different option than #92593. Please re-open your CL.

[fmayer]

Seems like we don't want to implement this after all.