Package: release.debian.org
Severity: normal
User: release.debian....@packages.debian.org
Usertags: unblock
Please unblock package perl
Changes:
perl (5.14.2-19) unstable; urgency=high
.
* [SECURITY] CVE-2013-1667: fix a rehashing DoS opportunity
against code that uses arbitrary user input as hash keys.
(Closes: #702296)
unblock perl/5.14.2-19
-- System Information:
Debian Release: 7.0
APT prefers unstable
APT policy: (500, 'unstable'), (500, 'testing'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386
Kernel: Linux 3.2.0-4-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=fi_FI.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
diff -Nru perl-5.14.2/debian/changelog perl-5.14.2/debian/changelog
--- perl-5.14.2/debian/changelog 2013-02-09 15:31:34.000000000 +0200
+++ perl-5.14.2/debian/changelog 2013-03-05 21:38:31.000000000 +0200
@@ -1,3 +1,11 @@
+perl (5.14.2-19) unstable; urgency=high
+
+ * [SECURITY] CVE-2013-1667: fix a rehashing DoS opportunity
+ against code that uses arbitrary user input as hash keys.
+ (Closes: #702296)
+
+ -- Niko Tyni <nt...@debian.org> Tue, 05 Mar 2013 21:38:26 +0200
+
perl (5.14.2-18) unstable; urgency=low
* Fix a squeeze regression with STDIN and signal handlers.
diff -Nru perl-5.14.2/debian/patches/fixes/hsplit-rehash.diff perl-5.14.2/debian/patches/fixes/hsplit-rehash.diff
--- perl-5.14.2/debian/patches/fixes/hsplit-rehash.diff 1970-01-01 02:00:00.000000000 +0200
+++ perl-5.14.2/debian/patches/fixes/hsplit-rehash.diff 2013-03-05 21:38:04.000000000 +0200
@@ -0,0 +1,173 @@
+From 5d86bf622ad5ac2cc69da54d76000a4618518410 Mon Sep 17 00:00:00 2001
+From: Yves Orton <demer...@gmail.com>
+Date: Tue, 12 Feb 2013 10:53:05 +0100
+Subject: 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)
+
+Bug-Debian: http://bugs.debian.org/702296
+Origin: upstream, http://perl5.git.perl.org/perl.git/commit/d59e31fc729d8a39a774f03bc6bc457029a7aef2
+Patch-Name: fixes/hsplit-rehash.diff
+---
+ 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;
diff -Nru perl-5.14.2/debian/patches/series perl-5.14.2/debian/patches/series
--- perl-5.14.2/debian/patches/series 2013-02-09 15:29:12.000000000 +0200
+++ perl-5.14.2/debian/patches/series 2013-03-05 21:38:04.000000000 +0200
@@ -76,3 +76,4 @@
fixes/digest-sha-doublefree.diff
fixes/64bitint-signedness-wraparound.diff
fixes/stdin-sigchld.diff
+fixes/hsplit-rehash.diff
