[PATCH] D31221: Bypass potential libc's sysconf interceptors
Aleksey Shlyapnikov via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Mar 22 12:05:59 PDT 2017
alekseyshl updated this revision to Diff 92676.
alekseyshl added a comment.
- Sync two ifdefs
https://reviews.llvm.org/D31221
Files:
lib/sanitizer_common/sanitizer_linux.cc
test/sanitizer_common/TestCases/Linux/sysconf_interceptor_bypass_test.cc
Index: test/sanitizer_common/TestCases/Linux/sysconf_interceptor_bypass_test.cc
===================================================================
--- /dev/null
+++ test/sanitizer_common/TestCases/Linux/sysconf_interceptor_bypass_test.cc
@@ -0,0 +1,25 @@
+// RUN: %clangxx -O2 %s -o %t && %run %t 2>&1 | FileCheck %s
+
+#include <stdio.h>
+
+// getauxval() used instead of sysconf() in GetPageSize() is defined starting
+// glbc version 2.16.
+#if defined(__GLIBC_PREREQ) && __GLIBC_PREREQ(2, 16)
+extern "C" long sysconf(int name) {
+ fprintf(stderr, "sysconf wrapper called\n");
+ return 0;
+}
+#endif // defined(__GLIBC_PREREQ) && __GLIBC_PREREQ(2, 16)
+
+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;
+}
Index: lib/sanitizer_common/sanitizer_linux.cc
===================================================================
--- lib/sanitizer_common/sanitizer_linux.cc
+++ lib/sanitizer_common/sanitizer_linux.cc
@@ -77,6 +77,20 @@
#include <sys/signal.h>
#endif
+#ifndef __GLIBC_PREREQ
+#define __GLIBC_PREREQ(x, y) 0
+#endif
+
+#if SANITIZER_LINUX && __GLIBC_PREREQ(2, 16)
+# define SANITIZER_USE_GETAUXVAL 1
+#else
+# define SANITIZER_USE_GETAUXVAL 0
+#endif
+
+#if SANITIZER_USE_GETAUXVAL
+#include <sys/auxv.h>
+#endif
+
#if SANITIZER_LINUX
// <linux/time.h>
struct kernel_timeval {
@@ -805,6 +819,8 @@
return 4096;
#elif SANITIZER_LINUX && (defined(__x86_64__) || defined(__i386__))
return EXEC_PAGESIZE;
+#elif SANITIZER_USE_GETAUXVAL
+ return getauxval(AT_PAGESZ);
#else
return sysconf(_SC_PAGESIZE); // EXEC_PAGESIZE may not be trustworthy.
#endif
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