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The mach exception data received in debugserver is not aligned to a doubleword
boundary. Most of these were fixed in 2017 by Vedant (`[MachException] Avoid
alignment UB, NFC`) but there was a codepath when debugserver logging is
enabled where we would still access the mach exception data without aligning it
first. This has been causing failures on the sanitizer greendragon bot for the
last few days from Jim's change in https://reviews.llvm.org/D157556 where he
is enabling LOG_EXCEPTIONS debugserver logging unconditionally (this should
prob be in a self.TraceOn() conditional, or maybe not even be in the test - it
looks like a debug print he forgot to remove) in the new test_shadow_listener
test.
https://green.lab.llvm.org/green/view/LLDB/job/lldb-cmake-sanitized/
Simplest fix, and it's only done when LOG_EXCEPTIONS is enabled, is to align
the data one-off for the logging.
I would have handed this to Jim to fix, but by the time I understood what the
actual failure was, it was nothing to fix it.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D158312
Files:
lldb/tools/debugserver/source/MacOSX/MachException.cpp
Index: lldb/tools/debugserver/source/MacOSX/MachException.cpp
===================================================================
--- lldb/tools/debugserver/source/MacOSX/MachException.cpp
+++ lldb/tools/debugserver/source/MacOSX/MachException.cpp
@@ -95,13 +95,20 @@
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();
Index: lldb/tools/debugserver/source/MacOSX/MachException.cpp
===================================================================
--- lldb/tools/debugserver/source/MacOSX/MachException.cpp
+++ lldb/tools/debugserver/source/MacOSX/MachException.cpp
@@ -95,13 +95,20 @@
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();
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