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From b52cdd7a8525325deba04554d8a00a578c397d56 Mon Sep 17 00:00:00 2001
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From: David Mitchell <davem@iabyn.com>
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Date: Thu, 11 Jul 2019 15:17:48 +0100
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Subject: [PATCH] threads::shared: fix leak
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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When assigning a shared reference value to a variable containing a
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shared string, the PV buffer in the shared space was leaked. For
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example:
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my $s :shared = "foo";
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my $t :shared = shared_clone(\"bar");
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$s = $t; # "foo" in shared space leaked
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This was showing up as failed smokes under ASan.
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Petr Písař: Ported to 1.60 from perl commit
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59c73bd3d62c5096a6f9b2e3cbe05e1ab4c158cf.
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Signed-off-by: Petr Písař <ppisar@redhat.com>
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---
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shared.xs | 15 +++++++++++----
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1 file changed, 11 insertions(+), 4 deletions(-)
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diff --git a/shared.xs b/shared.xs
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index 6cdf094..858c6d6 100644
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--- a/shared.xs
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+++ b/shared.xs
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@@ -818,12 +818,19 @@ sharedsv_scalar_store(pTHX_ SV *sv, SV *ssv)
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SV *obj = SvRV(sv);
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SV *sobj = Perl_sharedsv_find(aTHX_ obj);
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if (sobj) {
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+ SV* tmpref;
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SHARED_CONTEXT;
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- (void)SvUPGRADE(ssv, SVt_RV);
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- sv_setsv_nomg(ssv, &PL_sv_undef);
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+ /* Creating a tmp ref to sobj then assigning it to ssv ensures
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+ * that any previous contents of ssv are correctly freed
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+ * by sv_setsv(). Not sure if there is a better, API-legal way
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+ * to achieve this */
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+ tmpref = newSV_type(SVt_RV);
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+ SvRV_set(tmpref, sobj);
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+ SvROK_on(tmpref);
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+ SvREFCNT_inc_simple_NN(sobj);
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+ sv_setsv_nomg(ssv, tmpref);
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+ SvREFCNT_dec_NN(tmpref);
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- SvRV_set(ssv, SvREFCNT_inc(sobj));
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- SvROK_on(ssv);
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if (SvOBJECT(sobj)) {
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/* Remove any old blessing */
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SvREFCNT_dec(SvSTASH(sobj));
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--
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2.20.1
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