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notify ASAN about M:N threading stack switches

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In a similar way to how we do it with fibers in cont.c, we need to call
__sanitize_start_switch_fiber and __sanitize_finish_switch_fiber around
the call to coroutine_transfer to let ASAN save & restore the fake stack
pointer.

When a M:N thread is exiting, we pass `to_dead` to the new
coroutine_transfer0 function, so that we can pass NULL for saving the
stack pointer. This signals to ASAN that the fake stack can be freed
(otherwise it would be leaked)

[Bug #20220]
This commit is contained in:
KJ Tsanaktsidis 2024-01-28 17:15:43 +11:00
parent 19f615521d
commit 719db18b50
2 changed files with 36 additions and 7 deletions
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34
thread_pthread.c
View File

@ -333,6 +333,8 @@ static void timer_thread_wakeup(void);
static void timer_thread_wakeup_locked(rb_vm_t *vm);
static void timer_thread_wakeup_force(void);
static void thread_sched_switch(rb_thread_t *cth, rb_thread_t *next_th);
static void coroutine_transfer0(struct coroutine_context *transfer_from,
struct coroutine_context *transfer_to, bool to_dead);
#define thread_sched_dump(s) thread_sched_dump_(__FILE__, __LINE__, s)
@ -892,7 +894,7 @@ thread_sched_wait_running_turn(struct rb_thread_sched *sched, rb_thread_t *th, b
thread_sched_set_lock_owner(sched, NULL);
{
rb_ractor_set_current_ec(th->ractor, NULL);
coroutine_transfer(th->sched.context, nt->nt_context);
coroutine_transfer0(th->sched.context, nt->nt_context, false);
}
thread_sched_set_lock_owner(sched, th);
}
@ -1151,7 +1153,28 @@ rb_thread_sched_init(struct rb_thread_sched *sched, bool atfork)
}
static void
thread_sched_switch0(struct coroutine_context *current_cont, rb_thread_t *next_th, struct rb_native_thread *nt)
coroutine_transfer0(struct coroutine_context *transfer_from, struct coroutine_context *transfer_to, bool to_dead)
{
#ifdef RUBY_ASAN_ENABLED
void **fake_stack = to_dead ? NULL : &transfer_from->fake_stack;
__sanitizer_start_switch_fiber(fake_stack, transfer_to->stack_base, transfer_to->stack_size);
#endif
RBIMPL_ATTR_MAYBE_UNUSED()
struct coroutine_context *returning_from = coroutine_transfer(transfer_from, transfer_to);
/* if to_dead was passed, the caller is promising that this coroutine is finished and it should
* never be resumed! */
VM_ASSERT(!to_dead);
#ifdef RUBY_ASAN_ENABLED
__sanitizer_finish_switch_fiber(transfer_from->fake_stack,
(const void**)&returning_from->stack_base, &returning_from->stack_size);
#endif
}
static void
thread_sched_switch0(struct coroutine_context *current_cont, rb_thread_t *next_th, struct rb_native_thread *nt, bool to_dead)
{
VM_ASSERT(!nt->dedicated);
VM_ASSERT(next_th->nt == NULL);
@ -1160,7 +1183,8 @@ thread_sched_switch0(struct coroutine_context *current_cont, rb_thread_t *next_t
ruby_thread_set_native(next_th);
native_thread_assign(nt, next_th);
coroutine_transfer(current_cont, next_th->sched.context);
coroutine_transfer0(current_cont, next_th->sched.context, to_dead);
}
static void
@ -1169,7 +1193,7 @@ thread_sched_switch(rb_thread_t *cth, rb_thread_t *next_th)
struct rb_native_thread *nt = cth->nt;
native_thread_assign(NULL, cth);
RUBY_DEBUG_LOG("th:%u->%u on nt:%d", rb_th_serial(cth), rb_th_serial(next_th), nt->serial);
thread_sched_switch0(cth->sched.context, next_th, nt);
thread_sched_switch0(cth->sched.context, next_th, nt, cth->status == THREAD_KILLED);
}
#if VM_CHECK_MODE > 0
@ -2268,7 +2292,7 @@ nt_start(void *ptr)
if (next_th && next_th->nt == NULL) {
RUBY_DEBUG_LOG("nt:%d next_th:%d", (int)nt->serial, (int)next_th->serial);
thread_sched_switch0(nt->nt_context, next_th, nt);
thread_sched_switch0(nt->nt_context, next_th, nt, false);
}
else {
RUBY_DEBUG_LOG("no schedulable threads -- next_th:%p", next_th);

9
thread_pthread_mn.c
View File

@ -413,6 +413,11 @@ native_thread_check_and_create_shared(rb_vm_t *vm)
static COROUTINE
co_start(struct coroutine_context *from, struct coroutine_context *self)
{
#ifdef RUBY_ASAN_ENABLED
__sanitizer_finish_switch_fiber(self->fake_stack,
(const void**)&from->stack_base, &from->stack_size);
#endif
rb_thread_t *th = (rb_thread_t *)self->argument;
struct rb_thread_sched *sched = TH_SCHED(th);
VM_ASSERT(th->nt != NULL);
@ -447,13 +452,13 @@ co_start(struct coroutine_context *from, struct coroutine_context *self)
if (!has_ready_ractor && next_th && !next_th->nt) {
// switch to the next thread
thread_sched_set_lock_owner(sched, NULL);
thread_sched_switch0(th->sched.context, next_th, nt);
thread_sched_switch0(th->sched.context, next_th, nt, true);
th->sched.finished = true;
}
else {
// switch to the next Ractor
th->sched.finished = true;
coroutine_transfer(self, nt->nt_context);
coroutine_transfer0(self, nt->nt_context, true);
}
rb_bug("unreachable");
}