utf8::upgrade: Don't coerce undef arg

This fixes GH Perl#20419
khwilliamson · Nov 2, 2022 · b1dbe27 · b1dbe27
1 parent fce4124
commit b1dbe27
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Showing 2 changed files with 16 additions and 3 deletions.
diff --git a/lib/utf8.t b/lib/utf8.t
@@ -669,6 +669,9 @@ for(__PACKAGE__) {
 	eval { utf8::upgrade($_) };
 	is $@, "", 'no error with utf8::upgrade on read-only COW';
 }
+
+is(utf8::upgrade(undef), undef, "Returns undef for undef input"); # GH #20419
+
 # This one croaks, but not because the scalar is read-only
 eval "package \x{100};\n" . <<'END'
     for(__PACKAGE__) {

diff --git a/universal.c b/universal.c
@@ -593,11 +593,21 @@ XS(XS_utf8_upgrade)
         croak_xs_usage(cv, "sv");
     else {
         SV * const sv = ST(0);
-        STRLEN	RETVAL;
+        STRLEN	RETVAL = 0;
         dXSTARG;
 
-        RETVAL = sv_utf8_upgrade(sv);
-        XSprePUSH; PUSHi((IV)RETVAL);
+        XSprePUSH;
+        if (UNLIKELY(! sv)) {
+            XSRETURN_UNDEF;
+        }
+
+        SvGETMAGIC(sv);
+        if (UNLIKELY(! SvOK(sv))) {
+            XSRETURN_UNDEF;
+        }
+
+        RETVAL = sv_utf8_upgrade_nomg(sv);
+        PUSHi( (IV) RETVAL);
     }
     XSRETURN(1);
 }