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Fix JVM crash when Thread::current() returns nullptr (PROF-13072) #461

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Merged
jbachorik merged 4 commits into from
Apr 20, 2026
Merged

Fix JVM crash when Thread::current() returns nullptr (PROF-13072) #461

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009ab90
Fix JVM crash when Thread::current() returns nullptr (PROF-13072)
jbachorik Apr 10, 2026
abf7845
Fix native thread sample regression from PROF-13072 guard
jbachorik Apr 10, 2026
369c788
Fix stack-guard corruption on musl/aarch64/jdk11 (PROF-13072)
jbachorik Apr 10, 2026
4cdb7fa
address review: null-guard currentSignalSafe, fold tid into blocker, …
jbachorik Apr 20, 2026
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Fix stack-guard corruption on musl/aarch64/jdk11 (PROF-13072) 
Introduce start_window_and_register() noinline helper so that
start_routine_wrapper_spec() never has sigset_t (SignalBlocker)
on its own stack frame, preserving the original design that
prevents musl's stack-protector canary corruption on aarch64.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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@jbachorik @claude
jbachorik and claude committed Apr 10, 2026
commit 369c788e0071df53113471941fae0f3fbea68195
33 changes: 17 additions & 16 deletions ddprof-lib/src/main/cpp/libraryPatcher_linux.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,17 @@ static void init_thread_tls() {
ProfiledThread::initCurrentThread();
}

// Arm the CPU timer with profiling signals blocked and open the init window
// (PROF-13072). Kept noinline for the same stack-protector reason as
// delete_routine_info: SignalBlocker's sigset_t must not appear in
// start_routine_wrapper_spec's own stack frame on musl/aarch64.
__attribute__((noinline))
static void start_window_and_register(int tid) {
SignalBlocker blocker;
ProfiledThread::currentSignalSafe()->startInitWindow();
Profiler::registerThread(tid);
}

// Wrapper around the real start routine.
// The wrapper:
// 1. Register the newly created thread to profiler
Expand All @@ -82,22 +93,12 @@ static void init_thread_tls() {
__attribute__((visibility("hidden")))
static void* start_routine_wrapper_spec(void* args) {
RoutineInfo* thr = (RoutineInfo*)args;
func_start_routine routine;
void* params;
int tid;
{
// Keep signals blocked across delete_routine_info, init_thread_tls, and
// registerThread for the same reasons as start_routine_wrapper: ASAN
// lock-ordering and the JVM TLS race window (PROF-13072).
SignalBlocker blocker;
routine = thr->routine();
params = thr->args();
delete_routine_info(thr);
init_thread_tls();
tid = ProfiledThread::currentTid();
ProfiledThread::currentSignalSafe()->startInitWindow();
Profiler::registerThread(tid);
}
func_start_routine routine = thr->routine();
void* params = thr->args();
delete_routine_info(thr);
init_thread_tls();
int tid = ProfiledThread::currentTid();
start_window_and_register(tid);
void* result = routine(params);
Profiler::unregisterThread(tid);
ProfiledThread::release();
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