[Lldb-commits] [lldb] 1a2122e - Align mach exception data before accessing it

[Jason Molenda via lldb-commits]

Author: Jason Molenda
Date: 2023-08-18T15:34:13-07:00
New Revision: 1a2122e9e9d1d495fdf337a4a9445b61ca56df6f

URL: https://github.com/llvm/llvm-project/commit/1a2122e9e9d1d495fdf337a4a9445b61ca56df6f
DIFF: https://github.com/llvm/llvm-project/commit/1a2122e9e9d1d495fdf337a4a9445b61ca56df6f.diff

LOG: Align mach exception data before accessing it

The mach exception data may not be doubleword aligned when we receive
it.  We use memcpy to align it later in this method when we save
the data, but for printing the value at the top, we need to do the
same or ubsan can trigger when LOG_EXCEPTIONS is enabled in
debugserver.

Differential Revision: https://reviews.llvm.org/D158312

Added: 
    

Modified: 
    lldb/tools/debugserver/source/MacOSX/MachException.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/tools/debugserver/source/MacOSX/MachException.cpp b/lldb/tools/debugserver/source/MacOSX/MachException.cpp
index e760a3ef9faae3..eab4cdfc8b775d 100644
--- a/lldb/tools/debugserver/source/MacOSX/MachException.cpp
+++ b/lldb/tools/debugserver/source/MacOSX/MachException.cpp
@@ -95,13 +95,20 @@ catch_mach_exception_raise(mach_port_t exc_port, mach_port_t thread_port,
                            mach_exception_data_t exc_data,
                            mach_msg_type_number_t exc_data_count) {
   if (DNBLogCheckLogBit(LOG_EXCEPTIONS)) {
+    std::vector<uint64_t> exc_datas;
+    uint64_t tmp;
+    for (unsigned i = 0; i < exc_data_count; ++i) {
+      // Perform an unaligned copy.
+      memcpy(&tmp, &exc_data[i], sizeof(uint64_t));
+      exc_datas.push_back(tmp);
+    }
     DNBLogThreaded("::%s ( exc_port = 0x%4.4x, thd_port = 0x%4.4x, tsk_port = "
                    "0x%4.4x, exc_type = %d ( %s ), exc_data[%d] = { 0x%llx, "
                    "0x%llx })",
                    __FUNCTION__, exc_port, thread_port, task_port, exc_type,
                    MachException::Name(exc_type), exc_data_count,
-                   (uint64_t)(exc_data_count > 0 ? exc_data[0] : 0xBADDBADD),
-                   (uint64_t)(exc_data_count > 1 ? exc_data[1] : 0xBADDBADD));
+                   (uint64_t)(exc_data_count > 0 ? exc_datas[0] : 0xBADDBADD),
+                   (uint64_t)(exc_data_count > 1 ? exc_datas[1] : 0xBADDBADD));
   }
   g_message->exc_type = 0;
   g_message->exc_data.clear();