commit c0a0b1fce0b7229347f3f32ded8e666bf1da810c
author kcc <kcc> Thu Jan 31 01:40:14 2019 +0000
committer kcc <kcc> Thu Jan 31 01:40:14 2019 +0000
tree d3b4e4eff62511563d7a1be63ad8c3cb2f93bef4
parent 3418b94b7e5dbd54883a6e198c945f0c01c85925

[libFuzzer] set libFuzzer's own SEGV handler even one is already present, but call that handler from ours (unless we are unprotecting lazy counters). Call ProtectLazyCounters later, so that it runs after the initialization code in the target. 

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@352713 91177308-0d34-0410-b5e6-96231b3b80d8

FuzzerUtilPosix.cpp

diff --git a/FuzzerUtilPosix.cpp b/FuzzerUtilPosix.cpp
index 56b10ff..110785d 100644
--- a/FuzzerUtilPosix.cpp
+++ b/FuzzerUtilPosix.cpp
@@ -11,6 +11,7 @@
 #if LIBFUZZER_POSIX
 #include "FuzzerIO.h"
 #include "FuzzerInternal.h"
+#include "FuzzerTracePC.h"
 #include <cassert>
 #include <chrono>
 #include <cstring>
@@ -32,9 +33,14 @@
   Fuzzer::StaticAlarmCallback();
 }
 
-static void SegvHandler(int, siginfo_t *si, void *) {
+static void (*upstream_segv_handler)(int, siginfo_t *, void *);
+
+static void SegvHandler(int sig, siginfo_t *si, void *ucontext) {
   assert(si->si_signo == SIGSEGV);
-  Fuzzer::StaticSegvSignalCallback(si->si_addr);
+  if (TPC.UnprotectLazyCounters(si->si_addr)) return;
+  if (upstream_segv_handler)
+    return upstream_segv_handler(sig, si, ucontext);
+  Fuzzer::StaticCrashSignalCallback();
 }
 
 static void CrashHandler(int, siginfo_t *, void *) {
@@ -61,8 +67,11 @@
     exit(1);
   }
   if (sigact.sa_flags & SA_SIGINFO) {
-    if (sigact.sa_sigaction)
-      return;
+    if (sigact.sa_sigaction) {
+      if (signum != SIGSEGV)
+        return;
+      upstream_segv_handler = sigact.sa_sigaction;
+    }
   } else {
     if (sigact.sa_handler != SIG_DFL && sigact.sa_handler != SIG_IGN &&
         sigact.sa_handler != SIG_ERR)