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thread_pthread.c: allocate sigaltstack before pthread_create

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A new (not-initialized-yet) pthread attempts to allocate sigaltstack by
using xmalloc.  It may cause GC, but because the thread is not
initialized yet, ruby_native_thread_p() returns false, which leads to
"[FATAL] failed to allocate memory" and exit.

In fact, we can observe the error message in the log of OpenBSD CI:
https://rubyci.org/logs/rubyci.s3.amazonaws.com/openbsd-current/ruby-master/log/20200306T083005Z.log.html.gz

This changeset allocates sigaltstack before pthread is created.
This commit is contained in:
Yusuke Endoh 2020-03-06 21:32:42 +09:00
parent baaf681570
commit 0256e4f0f5
3 changed files with 27 additions and 8 deletions
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19
signal.c
View File

@ -547,14 +547,25 @@ rb_sigaltstack_size(void)
return size; return size;
} }
static int rb_sigaltstack_size_value = 0;
void *
rb_allocate_sigaltstack(void)
{
if (!rb_sigaltstack_size_value) {
rb_sigaltstack_size_value = rb_sigaltstack_size();
}
return xmalloc(rb_sigaltstack_size_value);
}
/* alternate stack for SIGSEGV */ /* alternate stack for SIGSEGV */
void * void *
rb_register_sigaltstack(void) rb_register_sigaltstack(void *altstack)
{ {
stack_t newSS, oldSS; stack_t newSS, oldSS;
newSS.ss_size = rb_sigaltstack_size(); newSS.ss_size = rb_sigaltstack_size_value;
newSS.ss_sp = xmalloc(newSS.ss_size); newSS.ss_sp = altstack;
newSS.ss_flags = 0; newSS.ss_flags = 0;
sigaltstack(&newSS, &oldSS); /* ignore error. */ sigaltstack(&newSS, &oldSS); /* ignore error. */
@ -1561,7 +1572,7 @@ Init_signal(void)
force_install_sighandler(SIGILL, (sighandler_t)sigill, &default_sigill_handler); force_install_sighandler(SIGILL, (sighandler_t)sigill, &default_sigill_handler);
#endif #endif
#ifdef SIGSEGV #ifdef SIGSEGV
RB_ALTSTACK_INIT(GET_VM()->main_altstack); RB_ALTSTACK_INIT(GET_VM()->main_altstack, rb_allocate_sigaltstack());
force_install_sighandler(SIGSEGV, (sighandler_t)sigsegv, &default_sigsegv_handler); force_install_sighandler(SIGSEGV, (sighandler_t)sigsegv, &default_sigsegv_handler);
#endif #endif
} }

5
thread_pthread.c
View File

@ -950,7 +950,7 @@ static void *
thread_start_func_1(void *th_ptr) thread_start_func_1(void *th_ptr)
{ {
rb_thread_t *th = th_ptr; rb_thread_t *th = th_ptr;
RB_ALTSTACK_INIT(void *altstack); RB_ALTSTACK_INIT(void *altstack, th->altstack);
#if USE_THREAD_CACHE #if USE_THREAD_CACHE
thread_start: thread_start:
#endif #endif
@ -1099,6 +1099,9 @@ native_thread_create(rb_thread_t *th)
const size_t stack_size = th->vm->default_params.thread_machine_stack_size + th->vm->default_params.thread_vm_stack_size; const size_t stack_size = th->vm->default_params.thread_machine_stack_size + th->vm->default_params.thread_vm_stack_size;
const size_t space = space_size(stack_size); const size_t space = space_size(stack_size);
#ifdef USE_SIGALTSTACK
th->altstack = rb_allocate_sigaltstack();
#endif
th->ec->machine.stack_maxsize = stack_size - space; th->ec->machine.stack_maxsize = stack_size - space;
CHECK_ERR(pthread_attr_init(&attr)); CHECK_ERR(pthread_attr_init(&attr));

11
vm_core.h
View File

@ -141,12 +141,13 @@
#if defined(SIGSEGV) && defined(HAVE_SIGALTSTACK) && defined(SA_SIGINFO) && !defined(__NetBSD__) #if defined(SIGSEGV) && defined(HAVE_SIGALTSTACK) && defined(SA_SIGINFO) && !defined(__NetBSD__)
# define USE_SIGALTSTACK # define USE_SIGALTSTACK
void *rb_register_sigaltstack(void); void *rb_allocate_sigaltstack(void);
# define RB_ALTSTACK_INIT(var) var = rb_register_sigaltstack() void *rb_register_sigaltstack(void *);
# define RB_ALTSTACK_INIT(var, altstack) var = rb_register_sigaltstack(altstack)
# define RB_ALTSTACK_FREE(var) xfree(var) # define RB_ALTSTACK_FREE(var) xfree(var)
# define RB_ALTSTACK(var) var # define RB_ALTSTACK(var) var
#else /* noop */ #else /* noop */
# define RB_ALTSTACK_INIT(var) # define RB_ALTSTACK_INIT(var, altstack)
# define RB_ALTSTACK_FREE(var) # define RB_ALTSTACK_FREE(var)
# define RB_ALTSTACK(var) (0) # define RB_ALTSTACK(var) (0)
#endif #endif
@ -974,6 +975,10 @@ typedef struct rb_thread_struct {
/* misc */ /* misc */
VALUE name; VALUE name;
#ifdef USE_SIGALTSTACK
void *altstack;
#endif
} rb_thread_t; } rb_thread_t;
typedef enum { typedef enum {