fix signal masking race in pthread_create with priority attributes

[musl] / src / thread / pthread_create.c

diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index e8d4a63..6cbf85b 100644 (file)
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -131,9 +131,14 @@ void __do_cleanup_pop(struct __ptcb *cb)
 static int start(void *p)
 {
        pthread_t self = p;
+       /* States for startlock:
+        * 0 = no need for start sync
+        * 1 = waiting for parent to do work
+        * 2 = failure in parent, child must abort
+        * 3 = success in parent, child must restore sigmask */
        if (self->startlock[0]) {
                __wait(self->startlock, 0, 1, 1);
-               if (self->startlock[0]) {
+               if (self->startlock[0] == 2) {
                        self->detached = 2;
                        pthread_exit(0);
                }
@@ -163,6 +168,8 @@ static void *dummy_tsd[1] = { 0 };
 weak_alias(dummy_tsd, __pthread_tsd_main);
 
 volatile int __block_new_threads = 0;
+size_t __default_stacksize = DEFAULT_STACK_SIZE;
+size_t __default_guardsize = DEFAULT_GUARD_SIZE;
 
 static FILE *volatile dummy_file = 0;
 weak_alias(dummy_file, __stdin_used);
@@ -186,10 +193,7 @@ int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict att
                | CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS
                | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED;
        int do_sched = 0;
-       pthread_attr_t attr = {
-               ._a_stacksize = DEFAULT_STACK_SIZE,
-               ._a_guardsize = DEFAULT_GUARD_SIZE,
-       };
+       pthread_attr_t attr = { 0 };
 
        if (!libc.can_do_threads) return ENOSYS;
        self = __pthread_self();
@@ -207,6 +211,11 @@ int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict att
        if (attrp && !c11) attr = *attrp;
 
        __acquire_ptc();
+       if (!attrp || c11) {
+               attr._a_stacksize = __default_stacksize;
+               attr._a_guardsize = __default_guardsize;
+       }
+
        if (__block_new_threads) __wait(&__block_new_threads, 0, 1, 1);
 
        if (attr._a_stackaddr) {
@@ -291,7 +300,7 @@ int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict att
        if (do_sched) {
                ret = __syscall(SYS_sched_setscheduler, new->tid,
                        attr._a_policy, &attr._a_prio);
-               a_store(new->startlock, ret<0 ? 2 : 0);
+               a_store(new->startlock, ret<0 ? 2 : 3);
                __wake(new->startlock, 1, 1);
                if (ret < 0) return -ret;
        }