$SIG{__WARN__} = sub { goto &foo } could recurse infinitely

p4raw-id: //depot/perl@25160

diff --git a/t/op/goto.t b/t/op/goto.t
index 7f502bd..082a165 100755 (executable)
--- a/t/op/goto.t
+++ b/t/op/goto.t
@@ -10,7 +10,7 @@ BEGIN {
 
 use warnings;
 use strict;
-plan tests => 56;
+plan tests => 57;
 
 our $foo;
 while ($?) {
@@ -436,3 +436,13 @@ eval 'goto &null';
 like($@, qr/Can't goto subroutine from an eval-string/, 'eval string');
 eval { goto &null };
 like($@, qr/Can't goto subroutine from an eval-block/, 'eval block');
+
+# [perl #36521] goto &foo in warn handler could defeat recursion avoider
+
+{
+    my $r = runperl(
+               stderr => 1,
+               prog => 'my $d; my $w = sub { return if $d++; warn q(bar)}; local $SIG{__WARN__} = sub { goto &$w; }; warn q(foo);'
+    );
+    like($r, qr/bar/, "goto &foo in warn");
+}

diff --git a/util.c b/util.c
index 74f5944..4f1a8e8 100644 (file)
--- a/util.c
+++ b/util.c
@@ -1278,6 +1278,8 @@ Perl_vwarn(pTHX_ const char* pat, va_list *args)
            SV *msg;
 
            ENTER;
+           SAVESPTR(PL_warnhook);
+           PL_warnhook = Nullsv;
            save_re_context();
            msg = newSVpvn(message, msglen);
            SvFLAGS(msg) |= utf8;