[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/D19576

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@267747 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/msan/msan.cc b/lib/msan/msan.cc
index cecbfe06a..52eda77e6 100644
--- a/lib/msan/msan.cc
+++ b/lib/msan/msan.cc
@@ -375,6 +375,7 @@ void __msan_init() {
   msan_init_is_running = 1;
   SanitizerToolName = "MemorySanitizer";
 
+  AvoidCVE_2016_2143();
   InitTlsSize();
 
   CacheBinaryName();