Bypass potential libc's sysconf wrappers for sysconf(_SC_PAGESIZE) call

Summary:
sysconf(_SC_PAGESIZE) is called very early, during sanitizer init and
any instrumented code (a wrapper/interceptor will likely be instrumented)
calling back to sanitizer before init is done will most surely crash.

Reviewers: eugenis

Subscribers: llvm-commits, kubamracek

Differential Revision: https://reviews.llvm.org/D31092

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@298305 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 21 insertions, 0 deletions

diff --git a/test/sanitizer_common/TestCases/Linux/sysconf_interceptor_bypass_test.cc b/test/sanitizer_common/TestCases/Linux/sysconf_interceptor_bypass_test.cc
new file mode 100644
index 000000000..97b6132e2
--- /dev/null
+++ b/test/sanitizer_common/TestCases/Linux/sysconf_interceptor_bypass_test.cc
@@ -0,0 +1,21 @@
+// RUN: %clangxx -O2 %s -o %t && %run %t 2>&1 | FileCheck %s
+
+#include <stdio.h>
+
+extern "C" long sysconf(int name) {
+  fprintf(stderr, "sysconf wrapper called\n");
+  return 0;
+}
+
+int main() {
+  // All we need to check is that the sysconf() interceptor defined above was
+  // not called. Should it get called, it will crash right there, any
+  // instrumented code executed before sanitizer init is finished will crash
+  // accessing non-initialized sanitizer internals. Even if it will not crash
+  // in some configuration, it should never be called anyway.
+  fprintf(stderr, "Passed\n");
+  // CHECK-NOT: sysconf wrapper called
+  // CHECK: Passed
+  // CHECK-NOT: sysconf wrapper called
+  return 0;
+}