[oe-commits] Ross Burton : perl: fix CVE-2013-1667
git at git.openembedded.org
git at git.openembedded.org
Mon Apr 29 16:55:59 UTC 2013
Module: openembedded-core.git
Branch: danny
Commit: ccc272a3f7bf240733dc3af1d8d7b870c55e1f5b
URL: http://git.openembedded.org/?p=openembedded-core.git&a=commit;h=ccc272a3f7bf240733dc3af1d8d7b870c55e1f5b
Author: Ross Burton <ross.burton at intel.com>
Date: Mon Apr 29 15:41:43 2013 +0100
perl: fix CVE-2013-1667
>From http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2013-1667:
"The rehash mechanism in Perl 5.8.2 through 5.16.x allows context-dependent
attackers to cause a denial of service (memory consumption and crash) via a
crafted hash key."
Patch taken from upstream git.
Signed-off-by: Ross Burton <ross.burton at intel.com>
---
.../perl/perl-5.14.2/cve-2013-1667.patch | 173 ++++++++++++++++++++
meta/recipes-devtools/perl/perl_5.14.2.bb | 1 +
2 files changed, 174 insertions(+), 0 deletions(-)
diff --git a/meta/recipes-devtools/perl/perl-5.14.2/cve-2013-1667.patch b/meta/recipes-devtools/perl/perl-5.14.2/cve-2013-1667.patch
new file mode 100644
index 0000000..a37cedb
--- /dev/null
+++ b/meta/recipes-devtools/perl/perl-5.14.2/cve-2013-1667.patch
@@ -0,0 +1,173 @@
+Upstream-Status: Backport
+Signed-off-by: Ross Burton <ross.burton at intel.com>
+
+From d59e31fc729d8a39a774f03bc6bc457029a7aef2 Mon Sep 17 00:00:00 2001
+From: Yves Orton <demerphq at gmail.com>
+Date: Tue, 12 Feb 2013 10:53:05 +0100
+Subject: [PATCH] Prevent premature hsplit() calls, and only trigger REHASH after hsplit()
+
+Triggering a hsplit due to long chain length allows an attacker
+to create a carefully chosen set of keys which can cause the hash
+to use 2 * (2**32) * sizeof(void *) bytes ram. AKA a DOS via memory
+exhaustion. Doing so also takes non trivial time.
+
+Eliminating this check, and only inspecting chain length after a
+normal hsplit() (triggered when keys>buckets) prevents the attack
+entirely, and makes such attacks relatively benign.
+
+(cherry picked from commit f1220d61455253b170e81427c9d0357831ca0fac)
+---
+ ext/Hash-Util-FieldHash/t/10_hash.t | 18 ++++++++++++++++--
+ hv.c | 35 ++++++++---------------------------
+ t/op/hash.t | 20 +++++++++++++++++---
+ 3 files changed, 41 insertions(+), 32 deletions(-)
+
+diff --git a/ext/Hash-Util-FieldHash/t/10_hash.t b/ext/Hash-Util-FieldHash/t/10_hash.t
+index 2cfb4e8..d58f053 100644
+--- a/ext/Hash-Util-FieldHash/t/10_hash.t
++++ b/ext/Hash-Util-FieldHash/t/10_hash.t
+@@ -38,15 +38,29 @@ use constant START => "a";
+
+ # some initial hash data
+ fieldhash my %h2;
+-%h2 = map {$_ => 1} 'a'..'cc';
++my $counter= "a";
++$h2{$counter++}++ while $counter ne 'cd';
+
+ ok (!Internals::HvREHASH(%h2),
+ "starting with pre-populated non-pathological hash (rehash flag if off)");
+
+ my @keys = get_keys(\%h2);
++my $buckets= buckets(\%h2);
+ $h2{$_}++ for @keys;
++$h2{$counter++}++ while buckets(\%h2) == $buckets; # force a split
+ ok (Internals::HvREHASH(%h2),
+- scalar(@keys) . " colliding into the same bucket keys are triggering rehash");
++ scalar(@keys) . " colliding into the same bucket keys are triggering rehash after split");
++
++# returns the number of buckets in a hash
++sub buckets {
++ my $hr = shift;
++ my $keys_buckets= scalar(%$hr);
++ if ($keys_buckets=~m!/([0-9]+)\z!) {
++ return 0+$1;
++ } else {
++ return 8;
++ }
++}
+
+ sub get_keys {
+ my $hr = shift;
+diff --git a/hv.c b/hv.c
+index 2be1feb..abb9d76 100644
+--- a/hv.c
++++ b/hv.c
+@@ -35,7 +35,8 @@ holds the key and hash value.
+ #define PERL_HASH_INTERNAL_ACCESS
+ #include "perl.h"
+
+-#define HV_MAX_LENGTH_BEFORE_SPLIT 14
++#define HV_MAX_LENGTH_BEFORE_REHASH 14
++#define SHOULD_DO_HSPLIT(xhv) ((xhv)->xhv_keys > (xhv)->xhv_max) /* HvTOTALKEYS(hv) > HvMAX(hv) */
+
+ static const char S_strtab_error[]
+ = "Cannot modify shared string table in hv_%s";
+@@ -794,29 +795,9 @@ Perl_hv_common(pTHX_ HV *hv, SV *keysv, const char *key, STRLEN klen,
+ if (masked_flags & HVhek_ENABLEHVKFLAGS)
+ HvHASKFLAGS_on(hv);
+
+- {
+- const HE *counter = HeNEXT(entry);
+-
+- xhv->xhv_keys++; /* HvTOTALKEYS(hv)++ */
+- if (!counter) { /* initial entry? */
+- } else if (xhv->xhv_keys > xhv->xhv_max) {
+- /* Use only the old HvKEYS(hv) > HvMAX(hv) condition to limit
+- bucket splits on a rehashed hash, as we're not going to
+- split it again, and if someone is lucky (evil) enough to
+- get all the keys in one list they could exhaust our memory
+- as we repeatedly double the number of buckets on every
+- entry. Linear search feels a less worse thing to do. */
+- hsplit(hv);
+- } else if(!HvREHASH(hv)) {
+- U32 n_links = 1;
+-
+- while ((counter = HeNEXT(counter)))
+- n_links++;
+-
+- if (n_links > HV_MAX_LENGTH_BEFORE_SPLIT) {
+- hsplit(hv);
+- }
+- }
++ xhv->xhv_keys++; /* HvTOTALKEYS(hv)++ */
++ if ( SHOULD_DO_HSPLIT(xhv) ) {
++ hsplit(hv);
+ }
+
+ if (return_svp) {
+@@ -1192,7 +1173,7 @@ S_hsplit(pTHX_ HV *hv)
+
+
+ /* Pick your policy for "hashing isn't working" here: */
+- if (longest_chain <= HV_MAX_LENGTH_BEFORE_SPLIT /* split worked? */
++ if (longest_chain <= HV_MAX_LENGTH_BEFORE_REHASH /* split worked? */
+ || HvREHASH(hv)) {
+ return;
+ }
+@@ -2831,8 +2812,8 @@ S_share_hek_flags(pTHX_ const char *str, I32 len, register U32 hash, int flags)
+
+ xhv->xhv_keys++; /* HvTOTALKEYS(hv)++ */
+ if (!next) { /* initial entry? */
+- } else if (xhv->xhv_keys > xhv->xhv_max /* HvKEYS(hv) > HvMAX(hv) */) {
+- hsplit(PL_strtab);
++ } else if ( SHOULD_DO_HSPLIT(xhv) ) {
++ hsplit(PL_strtab);
+ }
+ }
+
+diff --git a/t/op/hash.t b/t/op/hash.t
+index 278bea7..201260a 100644
+--- a/t/op/hash.t
++++ b/t/op/hash.t
+@@ -39,22 +39,36 @@ use constant THRESHOLD => 14;
+ use constant START => "a";
+
+ # some initial hash data
+-my %h2 = map {$_ => 1} 'a'..'cc';
++my %h2;
++my $counter= "a";
++$h2{$counter++}++ while $counter ne 'cd';
+
+ ok (!Internals::HvREHASH(%h2),
+ "starting with pre-populated non-pathological hash (rehash flag if off)");
+
+ my @keys = get_keys(\%h2);
++my $buckets= buckets(\%h2);
+ $h2{$_}++ for @keys;
++$h2{$counter++}++ while buckets(\%h2) == $buckets; # force a split
+ ok (Internals::HvREHASH(%h2),
+- scalar(@keys) . " colliding into the same bucket keys are triggering rehash");
++ scalar(@keys) . " colliding into the same bucket keys are triggering rehash after split");
++
++# returns the number of buckets in a hash
++sub buckets {
++ my $hr = shift;
++ my $keys_buckets= scalar(%$hr);
++ if ($keys_buckets=~m!/([0-9]+)\z!) {
++ return 0+$1;
++ } else {
++ return 8;
++ }
++}
+
+ sub get_keys {
+ my $hr = shift;
+
+ # the minimum of bits required to mount the attack on a hash
+ my $min_bits = log(THRESHOLD)/log(2);
+-
+ # if the hash has already been populated with a significant amount
+ # of entries the number of mask bits can be higher
+ my $keys = scalar keys %$hr;
+--
+1.7.4.1
diff --git a/meta/recipes-devtools/perl/perl_5.14.2.bb b/meta/recipes-devtools/perl/perl_5.14.2.bb
index 5e17661..dbfcf4c 100644
--- a/meta/recipes-devtools/perl/perl_5.14.2.bb
+++ b/meta/recipes-devtools/perl/perl_5.14.2.bb
@@ -69,6 +69,7 @@ SRC_URI = "http://www.cpan.org/src/5.0/perl-${PV}.tar.gz \
file://perl-archlib-exp.patch \
file://perl-fix-CVE-2012-5195.patch \
file://cve-2012-6329.patch \
+ file://cve-2013-1667.patch \
\
file://config.sh \
file://config.sh-32 \
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