[sanitizer] [SystemZ] Abort if the kernel might be vulnerable to CVE-2016-2143.

In short, CVE-2016-2143 will crash the machine if a process uses both >4TB
virtual addresses and fork().  ASan, TSan, and MSan will, by necessity, map
a sizable chunk of virtual address space, which is much larger than 4TB.
Even worse, sanitizers will always use fork() for llvm-symbolizer when a bug
is detected.  Disable all three by aborting on process initialization if
the running kernel version is not known to contain a fix.

Unfortunately, there's no reliable way to detect the fix without crashing
the kernel.  So, we rely on whitelisting - I've included a list of upstream
kernel versions that will work.  In case someone uses a distribution kernel
or applied the fix themselves, an override switch is also included.

Differential Revision: http://reviews.llvm.org/D18915

llvm-svn: 266297

1 files changed, 3 insertions, 0 deletions

diff --git a/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cc b/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cc
index c10fce5637e..e5c1ee04d07 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cc
+++ b/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cc
@@ -247,6 +247,9 @@ static void InitDataSeg() {
 #endif  // #ifndef SANITIZER_GO
 
 void InitializePlatformEarly() {
+#ifdef __s390x__
+  AvoidCVE_2016_2143();
+#endif
 #ifdef TSAN_RUNTIME_VMA
   vmaSize =
     (MostSignificantSetBitIndex(GET_CURRENT_FRAME()) + 1);