Pass down "stack start" variables from closer to the top of the stack

The implementation of `native_thread_init_stack` for the various
threading models can use the address of a local variable as part of the
calculation of the machine stack extents:

* pthreads uses it as a lower-bound on the start of the stack, because
  glibc (and maybe other libcs) can store its own data on the stack
  before calling into user code on thread creation.
* win32 uses it as an argument to VirtualQuery, which gets the extent of
  the memory mapping which contains the variable

However, the local being used for this is actually allocated _inside_
the `native_thread_init_stack` frame; that means the caller might
allocate a VALUE on the stack that actually lies outside the bounds
stored in machine.stack_{start,end}.

A local variable from one level above the topmost frame that stores
VALUEs on the stack must be drilled down into the call to
`native_thread_init_stack` to be used in the calculation. This probably
doesn't _really_ matter for the win32 case (they'll be in the same
memory mapping so VirtualQuery should return the same thing), but
definitely could matter for the pthreads case.

[Bug #20001]

1 files changed, 6 insertions, 6 deletions

diff --git a/thread_win32.c b/thread_win32.c
index bd983e0bd9..e92472cea9 100644
--- a/thread_win32.c
+++ b/thread_win32.c
@@ -582,7 +582,7 @@ rb_native_cond_destroy(rb_nativethread_cond_t *cond)
 }
 
 void
-ruby_init_stack(volatile VALUE *addr)
+ruby_init_stack(volatile void *addr)
 {
 }
 
@@ -594,20 +594,20 @@ COMPILER_WARNING_PUSH
 COMPILER_WARNING_IGNORED(-Wmaybe-uninitialized)
 #endif
 static inline SIZE_T
-query_memory_basic_info(PMEMORY_BASIC_INFORMATION mi)
+query_memory_basic_info(PMEMORY_BASIC_INFORMATION mi, void *local_in_parent_frame)
 {
-    return VirtualQuery(mi, mi, sizeof(*mi));
+    return VirtualQuery(local_in_parent_frame, mi, sizeof(*mi));
 }
 COMPILER_WARNING_POP
 
 static void
-native_thread_init_stack(rb_thread_t *th)
+native_thread_init_stack(rb_thread_t *th, void *local_in_parent_frame)
 {
     MEMORY_BASIC_INFORMATION mi;
     char *base, *end;
     DWORD size, space;
 
-    CHECK_ERR(query_memory_basic_info(&mi));
+    CHECK_ERR(query_memory_basic_info(&mi, local_in_parent_frame));
     base = mi.AllocationBase;
     end = mi.BaseAddress;
     end += mi.RegionSize;
@@ -638,7 +638,7 @@ thread_start_func_1(void *th_ptr)
     rb_thread_t *th = th_ptr;
     volatile HANDLE thread_id = th->nt->thread_id;
 
-    native_thread_init_stack(th);
+    native_thread_init_stack(th, &th);
     th->nt->interrupt_event = CreateEvent(0, TRUE, FALSE, 0);
 
     /* run */