Most importantly, don't try HvNAME(gp->gp_hv)

unless PL_stashcache exists, otherwise we get
an invalid read (detected by valgrind, and crashes
ext/threads/t/basic.t in Windows).

Also add a few if:s for the refcnt decrements,
no need to call Perl_sv_free() if there's nothing to free.

p4raw-id: //depot/perl@20292

1 files changed, 12 insertions, 8 deletions

diff --git a/gv.c b/gv.c
index a5dbb95ddc..8a9b803b1c 100644
--- a/gv.c
+++ b/gv.c
@@ -1252,14 +1252,18 @@ Perl_gp_free(pTHX_ GV *gv)
         return;
     }
 
-    SvREFCNT_dec(gp->gp_sv);
-    SvREFCNT_dec(gp->gp_av);
-    if(gp->gp_hv && HvNAME(gp->gp_hv) && PL_stashcache)
-        hv_delete(PL_stashcache, HvNAME(gp->gp_hv), strlen(HvNAME(gp->gp_hv)), G_DISCARD);
-    SvREFCNT_dec(gp->gp_hv);
-    SvREFCNT_dec(gp->gp_io);
-    SvREFCNT_dec(gp->gp_cv);
-    SvREFCNT_dec(gp->gp_form);
+    if (gp->gp_sv) SvREFCNT_dec(gp->gp_sv);
+    if (gp->gp_sv) SvREFCNT_dec(gp->gp_av);
+    if (gp->gp_hv) {
+	 if (PL_stashcache && HvNAME(gp->gp_hv))
+	      hv_delete(PL_stashcache,
+			HvNAME(gp->gp_hv), strlen(HvNAME(gp->gp_hv)),
+			G_DISCARD);
+	 SvREFCNT_dec(gp->gp_hv);
+    }
+    if (gp->gp_io)   SvREFCNT_dec(gp->gp_io);
+    if (gp->gp_cv)   SvREFCNT_dec(gp->gp_cv);
+    if (gp->gp_form) SvREFCNT_dec(gp->gp_form);
 
     Safefree(gp);
     GvGP(gv) = 0;