perl/perl-5.29.9-avoid-leak-assigning-regexp-to-non-COW-string.patch

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From 1385ac98c5f75358978bb05c2d6c4134413cf689 Mon Sep 17 00:00:00 2001
From: David Mitchell <davem@iabyn.com>
Date: Fri, 22 Mar 2019 17:38:48 +0000
Subject: [PATCH] avoid leak assigning regexp to non-COW string
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
In something like
$s = substr(.....); # $s now a non-COW SvPOK() SV
$r = qr/..../;
$s = $$r;
$s's previous string buffer would leak when an SVt_REGEXP type SV is
assigned to it.
Worse, if $s was an SVt_PVPV, it would fail an assert on debugging
builds.
The fix is to make sure any remaining stringy stuff is cleaned up
before copying the REGEXP.
Signed-off-by: Petr Písař <ppisar@redhat.com>
---
regcomp.c | 16 ++++++++++++++++
t/op/qr.t | 34 +++++++++++++++++++++++++++++++++-
2 files changed, 49 insertions(+), 1 deletion(-)
diff --git a/regcomp.c b/regcomp.c
index 15783541a4..e13da83673 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -20665,7 +20665,23 @@ Perl_reg_temp_copy(pTHX_ REGEXP *dsv, REGEXP *ssv)
if (!dsv)
dsv = (REGEXP*) newSV_type(SVt_REGEXP);
else {
+ assert(SvTYPE(dsv) == SVt_REGEXP || (SvTYPE(dsv) == SVt_PVLV));
+
+ /* our only valid caller, sv_setsv_flags(), should have done
+ * a SV_CHECK_THINKFIRST_COW_DROP() by now */
+ assert(!SvOOK(dsv));
+ assert(!SvIsCOW(dsv));
+ assert(!SvROK(dsv));
+
+ if (SvPVX_const(dsv)) {
+ if (SvLEN(dsv))
+ Safefree(SvPVX(dsv));
+ SvPVX(dsv) = NULL;
+ }
+ SvLEN_set(dsv, 0);
+ SvCUR_set(dsv, 0);
SvOK_off((SV *)dsv);
+
if (islv) {
/* For PVLVs, the head (sv_any) points to an XPVLV, while
* the LV's xpvlenu_rx will point to a regexp body, which
diff --git a/t/op/qr.t b/t/op/qr.t
index 32b9e3b23b..e03a465430 100644
--- a/t/op/qr.t
+++ b/t/op/qr.t
@@ -7,7 +7,7 @@ BEGIN {
require './test.pl';
}
-plan(tests => 34);
+plan(tests => 37);
sub r {
return qr/Good/;
@@ -135,3 +135,35 @@ sub {
};
}
pass("PVLV-as-REGEXP double-free of PVX");
+
+# a non-cow SVPV leaked it's string buffer when a REGEXP was assigned to
+# it. Give valgrind/ASan something to work on
+{
+ my $s = substr("ab",0,1); # generate a non-COW string
+ my $r1 = qr/x/;
+ $s = $$r1; # make sure "a" isn't leaked
+ pass("REGEXP leak");
+
+ my $dest = 0;
+ sub Foo99::DESTROY { $dest++ }
+
+ # ditto but make sure we don't leak a reference
+ {
+ my $ref = bless [], "Foo99";
+ my $r2 = qr/x/;
+ $ref = $$r2;
+ }
+ is($dest, 1, "REGEXP RV leak");
+
+ # and worse, assigning a REGEXP to an PVLV that had a string value
+ # caused an assert failure. Same code, but using $_[0] which is an
+ # lvalue, rather than $s.
+
+ my %h;
+ sub {
+ $_[0] = substr("ab",0,1); # generate a non-COW string
+ my $r = qr/x/;
+ $_[0] = $$r; # make sure "a" isn't leaked
+ }->($h{foo}); # passes PVLV to sub
+ is($h{foo}, "(?^:x)", "REGEXP PVLV leak");
+}
--
2.20.1