[asan] reallocate error_message_buffer when size is not enough

Author: Enna1

compiler-rt/lib/asan/asan_report.cpp

@@ -34,6 +34,7 @@ namespace __asan {
 static void (*error_report_callback)(const char*);
 static char *error_message_buffer = nullptr;
 static uptr error_message_buffer_pos = 0;
+static uptr error_message_buffer_size = kErrorMessageBufferSize;
 static Mutex error_message_buf_mutex;
 static const unsigned kAsanBuggyPcPoolSize = 25;
 static __sanitizer::atomic_uintptr_t AsanBuggyPcPool[kAsanBuggyPcPoolSize];
@@ -42,17 +43,23 @@ void AppendToErrorMessageBuffer(const char *buffer) {
   Lock l(&error_message_buf_mutex);
   if (!error_message_buffer) {
     error_message_buffer =
-      (char*)MmapOrDieQuietly(kErrorMessageBufferSize, __func__);
+        (char *)MmapOrDieQuietly(error_message_buffer_size, __func__);
     error_message_buffer_pos = 0;
   }
   uptr length = internal_strlen(buffer);
-  RAW_CHECK(kErrorMessageBufferSize >= error_message_buffer_pos);
-  uptr remaining = kErrorMessageBufferSize - error_message_buffer_pos;
-  internal_strncpy(error_message_buffer + error_message_buffer_pos,
-                   buffer, remaining);
-  error_message_buffer[kErrorMessageBufferSize - 1] = '\0';
-  // FIXME: reallocate the buffer instead of truncating the message.
-  error_message_buffer_pos += Min(remaining, length);
+  if (error_message_buffer_pos + length + 1 > error_message_buffer_size) {
+    uptr new_size = RoundUpToPowerOfTwo(error_message_buffer_size + length + 1);
+    RAW_CHECK(new_size > error_message_buffer_size);
+    char *new_buffer = (char *)MmapOrDieQuietly(new_size, __func__);
+    internal_memcpy(new_buffer, error_message_buffer,
+                    error_message_buffer_size);
+    UnmapOrDieQuietly(error_message_buffer, error_message_buffer_size);
+    error_message_buffer = new_buffer;
+    error_message_buffer_size = new_size;
+  }
+  internal_strncpy(error_message_buffer + error_message_buffer_pos, buffer,
+                   length + 1);
+  error_message_buffer_pos += length;
 }
 
 // ---------------------- Helper functions ----------------------- {{{1

compiler-rt/lib/sanitizer_common/sanitizer_common.h

@@ -94,7 +94,10 @@ void *MmapOrDie(uptr size, const char *mem_type, bool raw_report = false);
 inline void *MmapOrDieQuietly(uptr size, const char *mem_type) {
   return MmapOrDie(size, mem_type, /*raw_report*/ true);
 }
-void UnmapOrDie(void *addr, uptr size);
+void UnmapOrDie(void *addr, uptr size, bool raw_report = false);
+inline void UnmapOrDieQuietly(void *addr, uptr size) {
+  UnmapOrDie(addr, size, /*raw_report*/ true);
+}
 // Behaves just like MmapOrDie, but tolerates out of memory condition, in that
 // case returns nullptr.
 void *MmapOrDieOnFatalError(uptr size, const char *mem_type);

compiler-rt/lib/sanitizer_common/sanitizer_posix.cpp

@@ -54,12 +54,12 @@ void *MmapOrDie(uptr size, const char *mem_type, bool raw_report) {
   return (void *)res;
 }
 
-void UnmapOrDie(void *addr, uptr size) {
+void UnmapOrDie(void *addr, uptr size, bool raw_report) {
   if (!addr || !size) return;
   uptr res = internal_munmap(addr, size);
   int reserrno;
   if (UNLIKELY(internal_iserror(res, &reserrno)))
-    ReportMunmapFailureAndDie(addr, size, reserrno);
+    ReportMunmapFailureAndDie(addr, size, reserrno, raw_report);
   DecreaseTotalMmap(size);
 }
 
@@ -85,8 +85,8 @@ void *MmapAlignedOrDieOnFatalError(uptr size, uptr alignment,
   CHECK(IsPowerOfTwo(size));
   CHECK(IsPowerOfTwo(alignment));
   uptr map_size = size + alignment;
-  // mmap maps entire pages and rounds up map_size needs to be a an integral 
-  // number of pages. 
+  // mmap maps entire pages and rounds up map_size needs to be a an integral
+  // number of pages.
   // We need to be aware of this size for calculating end and for unmapping
   // fragments before and after the alignment region.
   map_size = RoundUpTo(map_size, GetPageSizeCached());