[compiler-rt] [sanitizer] Disable writes to log files for binaries in a secure context. (PR #92593)

[via llvm-commits]

https://github.com/bigb4ng updated https://github.com/llvm/llvm-project/pull/92593

>From ca9856c2f6616851bfd0bc6aac351bb6f2742fd8 Mon Sep 17 00:00:00 2001
From: bigb4ng <130478744+bigb4ng at users.noreply.github.com>
Date: Fri, 17 May 2024 07:26:39 +0300
Subject: [PATCH] [sanitizer] Disable using log_path with AT_SECURE.

Fix for https://github.com/google/sanitizers/issues/1130.

An original issue described by Szabolcs Nagy at https://seclists.org/oss-sec/2016/q1/363.
---
 .../lib/sanitizer_common/sanitizer_file.cpp      | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_file.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_file.cpp
index 7ef499ce07b13..3c0e0b8d5cc59 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_file.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_file.cpp
@@ -17,8 +17,9 @@
 
 #if !SANITIZER_FUCHSIA
 
-#include "sanitizer_common.h"
-#include "sanitizer_file.h"
+#  include "sanitizer_common.h"
+#  include "sanitizer_file.h"
+#  include "sanitizer_getauxval.h"
 #  include "sanitizer_interface_internal.h"
 
 namespace __sanitizer {
@@ -104,6 +105,17 @@ void ReportFile::SetReportPath(const char *path) {
     }
   }
 
+  // This is so we can use the weak definition from sanitizer_getauxval.h
+  if (&getauxval && getauxval(/* AT_SECURE */ 23) != 0 && path &&
+      internal_strcmp(path, "stderr") != 0 &&
+      internal_strcmp(path, "stdout") != 0) {
+    Report(
+        "ERROR: log_path must be 'stderr' or 'stdout' for AT_SECURE "
+        "(e.g. setuid binaries), is '%s'\n",
+        path);
+    Die();
+  }
+
   SpinMutexLock l(mu);
   if (fd != kStdoutFd && fd != kStderrFd && fd != kInvalidFd)
     CloseFile(fd);