sanitizers: consistently check result of MmapFixedNoReserve

MmapFixedNoReserve does not terminate process on failure.
Failure to check its result and die will always lead to harder
to debug crashes later in execution. This was observed in Go
processes due to some address space conflicts.

Consistently check result of MmapFixedNoReserve.
While we are here also add warn_unused_result attribute
to prevent such bugs in future and change return type to bool
as that's what all callers want.

Reviewed in https://reviews.llvm.org/D49367



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@337531 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 14 insertions, 8 deletions

diff --git a/lib/sanitizer_common/sanitizer_common.h b/lib/sanitizer_common/sanitizer_common.h
index c37db56d3..3b999edfb 100644
--- a/lib/sanitizer_common/sanitizer_common.h
+++ b/lib/sanitizer_common/sanitizer_common.h
@@ -88,8 +88,8 @@ void UnmapOrDie(void *addr, uptr size);
 // Behaves just like MmapOrDie, but tolerates out of memory condition, in that
 // case returns nullptr.
 void *MmapOrDieOnFatalError(uptr size, const char *mem_type);
-void *MmapFixedNoReserve(uptr fixed_addr, uptr size,
-                         const char *name = nullptr);
+bool MmapFixedNoReserve(uptr fixed_addr, uptr size, const char *name = nullptr)
+     WARN_UNUSED_RESULT;
 void *MmapNoReserveOrDie(uptr size, const char *mem_type);
 void *MmapFixedOrDie(uptr fixed_addr, uptr size);
 // Behaves just like MmapFixedOrDie, but tolerates out of memory condition, in
diff --git a/lib/sanitizer_common/sanitizer_internal_defs.h b/lib/sanitizer_common/sanitizer_internal_defs.h
index a955733fb..e4aa07b25 100644
--- a/lib/sanitizer_common/sanitizer_internal_defs.h
+++ b/lib/sanitizer_common/sanitizer_internal_defs.h
@@ -211,6 +211,7 @@ typedef u64 tid_t;
 # define LIKELY(x) (x)
 # define UNLIKELY(x) (x)
 # define PREFETCH(x) /* _mm_prefetch(x, _MM_HINT_NTA) */ (void)0
+# define WARN_UNUSED_RESULT
 #else  // _MSC_VER
 # define ALWAYS_INLINE inline __attribute__((always_inline))
 # define ALIAS(x) __attribute__((alias(x)))
@@ -229,6 +230,7 @@ typedef u64 tid_t;
 # else
 #  define PREFETCH(x) __builtin_prefetch(x)
 # endif
+# define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
 #endif  // _MSC_VER
 
 #if !defined(_MSC_VER) || defined(__clang__)
diff --git a/lib/sanitizer_common/sanitizer_posix_libcdep.cc b/lib/sanitizer_common/sanitizer_posix_libcdep.cc
index eaf157881..266e9bdba 100644
--- a/lib/sanitizer_common/sanitizer_posix_libcdep.cc
+++ b/lib/sanitizer_common/sanitizer_posix_libcdep.cc
@@ -328,7 +328,7 @@ int GetNamedMappingFd(const char *name, uptr size) {
 }
 #endif
 
-void *MmapFixedNoReserve(uptr fixed_addr, uptr size, const char *name) {
+bool MmapFixedNoReserve(uptr fixed_addr, uptr size, const char *name) {
   int fd = name ? GetNamedMappingFd(name, size) : -1;
   unsigned flags = MAP_PRIVATE | MAP_FIXED | MAP_NORESERVE;
   if (fd == -1) flags |= MAP_ANON;
@@ -338,12 +338,14 @@ void *MmapFixedNoReserve(uptr fixed_addr, uptr size, const char *name) {
                          RoundUpTo(size, PageSize), PROT_READ | PROT_WRITE,
                          flags, fd, 0);
   int reserrno;
-  if (internal_iserror(p, &reserrno))
+  if (internal_iserror(p, &reserrno)) {
     Report("ERROR: %s failed to "
            "allocate 0x%zx (%zd) bytes at address %zx (errno: %d)\n",
            SanitizerToolName, size, size, fixed_addr, reserrno);
+    return false;
+  }
   IncreaseTotalMmap(size);
-  return (void *)p;
+  return true;
 }
 
 uptr ReservedAddressRange::Init(uptr size, const char *name, uptr fixed_addr) {
diff --git a/lib/sanitizer_common/sanitizer_win.cc b/lib/sanitizer_common/sanitizer_win.cc
index cacc0d12f..b8060b2e6 100644
--- a/lib/sanitizer_common/sanitizer_win.cc
+++ b/lib/sanitizer_common/sanitizer_win.cc
@@ -202,7 +202,7 @@ void *MmapAlignedOrDieOnFatalError(uptr size, uptr alignment,
   return (void *)mapped_addr;
 }
 
-void *MmapFixedNoReserve(uptr fixed_addr, uptr size, const char *name) {
+bool MmapFixedNoReserve(uptr fixed_addr, uptr size, const char *name) {
   // FIXME: is this really "NoReserve"? On Win32 this does not matter much,
   // but on Win64 it does.
   (void)name;  // unsupported
@@ -215,11 +215,13 @@ void *MmapFixedNoReserve(uptr fixed_addr, uptr size, const char *name) {
   void *p = VirtualAlloc((LPVOID)fixed_addr, size, MEM_RESERVE | MEM_COMMIT,
                          PAGE_READWRITE);
 #endif
-  if (p == 0)
+  if (p == 0) {
     Report("ERROR: %s failed to "
            "allocate %p (%zd) bytes at %p (error code: %d)\n",
            SanitizerToolName, size, size, fixed_addr, GetLastError());
-  return p;
+    return false;
+  }
+  return true;
 }
 
 // Memory space mapped by 'MmapFixedOrDie' must have been reserved by