[asan] When catching a signal caused by a memory access, print if it's a READ or a WRITE. This touches win/mac files which I have not tested, if a win/mac bot fails I'll try to quick-fix

llvm-svn: 259741

compiler-rt/lib/asan/asan_report.cc

@@ -761,10 +761,15 @@ void ReportDeadlySignal(const char *description, const SignalContext &sig) {
       " (pc %p bp %p sp %p T%d)\n",
       description, (void *)sig.addr, (void *)sig.pc, (void *)sig.bp,
       (void *)sig.sp, GetCurrentTidOrInvalid());
-  if (sig.pc < GetPageSizeCached()) {
-    Report("Hint: pc points to the zero page.\n");
-  }
   Printf("%s", d.EndWarning());
+  if (sig.pc < GetPageSizeCached())
+    Report("Hint: pc points to the zero page.\n");
+  if (sig.is_memory_access) {
+    Report("The signal is caused by a %s memory access.\n",
+           sig.is_write ? "WRITE" : "READ");
+    if (sig.addr < GetPageSizeCached())
+      Report("Hint: address points to the zero page.\n");
+  }
   GET_STACK_TRACE_SIGNAL(sig);
   stack.Print();
   MaybeDumpInstructionBytes(sig.pc);

compiler-rt/lib/sanitizer_common/sanitizer_common.h

@@ -749,15 +749,20 @@ struct SignalContext {
   uptr pc;
   uptr sp;
   uptr bp;
+  bool is_memory_access;
+  bool is_write;
 
-  SignalContext(void *context, uptr addr, uptr pc, uptr sp, uptr bp) :
-      context(context), addr(addr), pc(pc), sp(sp), bp(bp) {
-  }
+  SignalContext(void *context, uptr addr, uptr pc, uptr sp, uptr bp,
+                bool is_memory_access, bool is_write)
+      : context(context), addr(addr), pc(pc), sp(sp), bp(bp),
+      is_memory_access(is_memory_access), is_write(is_write) {}
 
   // Creates signal context in a platform-specific manner.
   static SignalContext Create(void *siginfo, void *context);
 };
 
+// Returns true if the "context" indicates a memory write.
+bool GetSigContextWriteFlag(void *context);
 void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp);
 
 void DisableReexec();

compiler-rt/lib/sanitizer_common/sanitizer_linux.cc

@@ -1155,6 +1155,11 @@ void *internal_start_thread(void (*func)(void *), void *arg) { return 0; }
 void internal_join_thread(void *th) {}
 #endif
 
+bool GetSigContextWriteFlag(void *context) {
+  ucontext_t *ucontext = (ucontext_t*)context;
+  return ucontext->uc_mcontext.gregs[REG_ERR] & 2;
+}
+
 void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
 #if defined(__arm__)
   ucontext_t *ucontext = (ucontext_t*)context;

compiler-rt/lib/sanitizer_common/sanitizer_mac.cc

@@ -491,6 +491,10 @@ void LogFullErrorReport(const char *buffer) {
   // The report is added to CrashLog as part of logging all of Printf output.
 }
 
+bool GetSigContextWriteFlag(void *context) {
+  return false;  // FIXME: implement this.
+}
+
 void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
   ucontext_t *ucontext = (ucontext_t*)context;
 # if defined(__aarch64__)

compiler-rt/lib/sanitizer_common/sanitizer_posix.cc

@@ -323,10 +323,13 @@ bool GetCodeRangeForFile(const char *module, uptr *start, uptr *end) {
 }
 
 SignalContext SignalContext::Create(void *siginfo, void *context) {
-  uptr addr = (uptr)((siginfo_t*)siginfo)->si_addr;
+  auto si = (siginfo_t*)siginfo;
+  uptr addr = (uptr)si->si_addr;
   uptr pc, sp, bp;
   GetPcSpBp(context, &pc, &sp, &bp);
-  return SignalContext(context, addr, pc, sp, bp);
+  bool is_write = GetSigContextWriteFlag(context);
+  bool is_memory_access = si->si_signo == SIGSEGV;
+  return SignalContext(context, addr, pc, sp, bp, is_memory_access, is_write);
 }
 
 } // namespace __sanitizer

compiler-rt/lib/sanitizer_common/sanitizer_win.cc

@@ -744,7 +744,10 @@ SignalContext SignalContext::Create(void *siginfo, void *context) {
 #endif
   uptr access_addr = exception_record->ExceptionInformation[1];
 
-  return SignalContext(context, access_addr, pc, sp, bp);
+  bool is_write = false;  // FIXME: compute this.
+  bool is_memory_access = false;  // FIXME: compute this.
+  return SignalContext(context, access_addr, pc, sp, bp, is_memory_access,
+                       is_write);
 }
 
 uptr ReadBinaryName(/*out*/char *buf, uptr buf_len) {

compiler-rt/test/asan/TestCases/Linux/segv_read_write.c

@@ -0,0 +1,17 @@
+// RUN: %clangxx_asan -O0 %s -o %t
+// RUN: not %run %t       2>&1 | FileCheck %s --check-prefix=READ
+// RUN: not %run %t write 2>&1 | FileCheck %s --check-prefix=WRITE
+
+static volatile int sink;
+__attribute__((noinline)) void Read(int *ptr) { sink = *ptr; }
+__attribute__((noinline)) void Write(int *ptr) { *ptr = 0; }
+int main(int argc, char **argv) {
+  if (argc == 1)
+    Read((int *)0);
+  else
+    Write((int *)0);
+}
+// READ: AddressSanitizer: SEGV on unknown address
+// READ: The signal is caused by a READ memory access.
+// WRITE: AddressSanitizer: SEGV on unknown address
+// WRITE: The signal is caused by a WRITE memory access.