[compiler-rt] [asan] Use InternalMmapVector for error_message_buffer, reallocate wh… (PR #77488)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: Enna1 (Enna1)

<details>
<summary>Changes</summary>

…en the size of error_message_buffer is not enough

---
Full diff: https://github.com/llvm/llvm-project/pull/77488.diff


1 Files Affected:

- (modified) compiler-rt/lib/asan/asan_report.cpp (+13-16) 


``````````diff
diff --git a/compiler-rt/lib/asan/asan_report.cpp b/compiler-rt/lib/asan/asan_report.cpp
index 7603e8131154ba..1cd21bfbc0bfeb 100644
--- a/compiler-rt/lib/asan/asan_report.cpp
+++ b/compiler-rt/lib/asan/asan_report.cpp
@@ -32,8 +32,7 @@ namespace __asan {
 
 // -------------------- User-specified callbacks ----------------- {{{1
 static void (*error_report_callback)(const char*);
-static char *error_message_buffer = nullptr;
-static uptr error_message_buffer_pos = 0;
+static InternalMmapVector<char> *error_message_buffer = nullptr;
 static Mutex error_message_buf_mutex;
 static const unsigned kAsanBuggyPcPoolSize = 25;
 static __sanitizer::atomic_uintptr_t AsanBuggyPcPool[kAsanBuggyPcPoolSize];
@@ -42,17 +41,15 @@ void AppendToErrorMessageBuffer(const char *buffer) {
   Lock l(&error_message_buf_mutex);
   if (!error_message_buffer) {
     error_message_buffer =
-      (char*)MmapOrDieQuietly(kErrorMessageBufferSize, __func__);
-    error_message_buffer_pos = 0;
+        new (GetGlobalLowLevelAllocator()) InternalMmapVector<char>();
+    error_message_buffer->reserve(kErrorMessageBufferSize);
+    error_message_buffer->push_back('\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);
+  uptr error_message_buffer_len = error_message_buffer->size() - 1;
+  uptr buffer_len = internal_strlen(buffer);
+  error_message_buffer->resize(error_message_buffer_len + buffer_len + 1);
+  internal_memcpy(error_message_buffer->data() + error_message_buffer_len,
+                  buffer, buffer_len + 1);
 }
 
 // ---------------------- Helper functions ----------------------- {{{1
@@ -158,14 +155,14 @@ class ScopedInErrorReport {
 
     // Copy the message buffer so that we could start logging without holding a
     // lock that gets acquired during printing.
-    InternalMmapVector<char> buffer_copy(kErrorMessageBufferSize);
+    InternalScopedString buffer_copy;
     {
       Lock l(&error_message_buf_mutex);
-      internal_memcpy(buffer_copy.data(),
-                      error_message_buffer, kErrorMessageBufferSize);
+      buffer_copy.Append(error_message_buffer->data());
       // Clear error_message_buffer so that if we find other errors
       // we don't re-log this error.
-      error_message_buffer_pos = 0;
+      error_message_buffer->clear();
+      error_message_buffer->push_back('\0');
     }
 
     LogFullErrorReport(buffer_copy.data());

``````````

</details>


https://github.com/llvm/llvm-project/pull/77488