merge revision(s) f336a3eb6c76890f3d8f878725b3d328c8fdcf33: [Backport #18126]

	Use free instead of xfree to free altstack

	The altstack memory of a thread may be free'ed even after the VM is
	destructed. After that, GC is no longer available, so calling xfree
	may lead to a segfault.

	This changeset uses the bare free function to free the altstack memory
	instead of xfree. [Bug #18126]
	---
	 signal.c  | 5 ++++-
	 vm_core.h | 2 +-
	 2 files changed, 5 insertions(+), 2 deletions(-)

3 files changed, 6 insertions, 3 deletions

diff --git a/signal.c b/signal.c
index 6eea6aabe2..c13bc19f1c 100644
--- a/signal.c
+++ b/signal.c
@@ -557,10 +557,13 @@ static int rb_sigaltstack_size_value = 0;
 void *
 rb_allocate_sigaltstack(void)
 {
+    void *altstack;
     if (!rb_sigaltstack_size_value) {
 	rb_sigaltstack_size_value = rb_sigaltstack_size();
     }
-    return xmalloc(rb_sigaltstack_size_value);
+    altstack = malloc(rb_sigaltstack_size_value);
+    if (!altstack) rb_memerror();
+    return altstack;
 }
 
 /* alternate stack for SIGSEGV */
diff --git a/version.h b/version.h
index 687a8ef015..ea49bd215d 100644
--- a/version.h
+++ b/version.h
@@ -12,7 +12,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 3
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 131
+#define RUBY_PATCHLEVEL 132
 
 #define RUBY_RELEASE_YEAR 2021
 #define RUBY_RELEASE_MONTH 9
diff --git a/vm_core.h b/vm_core.h
index a7644eb658..edf6da1076 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -136,7 +136,7 @@
 void *rb_allocate_sigaltstack(void);
 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) free(var)
 #  define RB_ALTSTACK(var)  var
 #else /* noop */
 #  define RB_ALTSTACK_INIT(var, altstack)