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1 files changed, 178 insertions, 0 deletions
diff --git a/meta/recipes-devtools/perl/perl-5.14.3/0001-Prevent-premature-hsplit-calls-and-only-trigger-REHA.patch b/meta/recipes-devtools/perl/perl-5.14.3/0001-Prevent-premature-hsplit-calls-and-only-trigger-REHA.patch
new file mode 100644
index 0000000..4357c2e
--- /dev/null
+++ b/meta/recipes-devtools/perl/perl-5.14.3/0001-Prevent-premature-hsplit-calls-and-only-trigger-REHA.patch
@@ -0,0 +1,178 @@
1From d59e31fc729d8a39a774f03bc6bc457029a7aef2 Mon Sep 17 00:00:00 2001
2From: Yves Orton <demerphq@gmail.com>
3Date: Tue, 12 Feb 2013 10:53:05 +0100
4Subject: [PATCH] Prevent premature hsplit() calls, and only trigger REHASH
5 after hsplit()
6
7Triggering a hsplit due to long chain length allows an attacker
8to create a carefully chosen set of keys which can cause the hash
9to use 2 * (2**32) * sizeof(void *) bytes ram. AKA a DOS via memory
10exhaustion. Doing so also takes non trivial time.
11
12Eliminating this check, and only inspecting chain length after a
13normal hsplit() (triggered when keys>buckets) prevents the attack
14entirely, and makes such attacks relatively benign.
15
16(cherry picked from commit f1220d61455253b170e81427c9d0357831ca0fac)
17
18Upstream-Status: Backport
19
20Signed-off-by: Saul Wold <sgw@linux.intel.com>
21
22
23---
24 ext/Hash-Util-FieldHash/t/10_hash.t | 18 ++++++++++++++++--
25 hv.c | 35 ++++++++---------------------------
26 t/op/hash.t | 20 +++++++++++++++++---
27 3 files changed, 41 insertions(+), 32 deletions(-)
28
29diff --git a/ext/Hash-Util-FieldHash/t/10_hash.t b/ext/Hash-Util-FieldHash/t/10_hash.t
30index 2cfb4e8..d58f053 100644
31--- a/ext/Hash-Util-FieldHash/t/10_hash.t
32+++ b/ext/Hash-Util-FieldHash/t/10_hash.t
33@@ -38,15 +38,29 @@ use constant START => "a";
34
35 # some initial hash data
36 fieldhash my %h2;
37-%h2 = map {$_ => 1} 'a'..'cc';
38+my $counter= "a";
39+$h2{$counter++}++ while $counter ne 'cd';
40
41 ok (!Internals::HvREHASH(%h2),
42 "starting with pre-populated non-pathological hash (rehash flag if off)");
43
44 my @keys = get_keys(\%h2);
45+my $buckets= buckets(\%h2);
46 $h2{$_}++ for @keys;
47+$h2{$counter++}++ while buckets(\%h2) == $buckets; # force a split
48 ok (Internals::HvREHASH(%h2),
49- scalar(@keys) . " colliding into the same bucket keys are triggering rehash");
50+ scalar(@keys) . " colliding into the same bucket keys are triggering rehash after split");
51+
52+# returns the number of buckets in a hash
53+sub buckets {
54+ my $hr = shift;
55+ my $keys_buckets= scalar(%$hr);
56+ if ($keys_buckets=~m!/([0-9]+)\z!) {
57+ return 0+$1;
58+ } else {
59+ return 8;
60+ }
61+}
62
63 sub get_keys {
64 my $hr = shift;
65diff --git a/hv.c b/hv.c
66index 2be1feb..abb9d76 100644
67--- a/hv.c
68+++ b/hv.c
69@@ -35,7 +35,8 @@ holds the key and hash value.
70 #define PERL_HASH_INTERNAL_ACCESS
71 #include "perl.h"
72
73-#define HV_MAX_LENGTH_BEFORE_SPLIT 14
74+#define HV_MAX_LENGTH_BEFORE_REHASH 14
75+#define SHOULD_DO_HSPLIT(xhv) ((xhv)->xhv_keys > (xhv)->xhv_max) /* HvTOTALKEYS(hv) > HvMAX(hv) */
76
77 static const char S_strtab_error[]
78 = "Cannot modify shared string table in hv_%s";
79@@ -794,29 +795,9 @@ Perl_hv_common(pTHX_ HV *hv, SV *keysv, const char *key, STRLEN klen,
80 if (masked_flags & HVhek_ENABLEHVKFLAGS)
81 HvHASKFLAGS_on(hv);
82
83- {
84- const HE *counter = HeNEXT(entry);
85-
86- xhv->xhv_keys++; /* HvTOTALKEYS(hv)++ */
87- if (!counter) { /* initial entry? */
88- } else if (xhv->xhv_keys > xhv->xhv_max) {
89- /* Use only the old HvKEYS(hv) > HvMAX(hv) condition to limit
90- bucket splits on a rehashed hash, as we're not going to
91- split it again, and if someone is lucky (evil) enough to
92- get all the keys in one list they could exhaust our memory
93- as we repeatedly double the number of buckets on every
94- entry. Linear search feels a less worse thing to do. */
95- hsplit(hv);
96- } else if(!HvREHASH(hv)) {
97- U32 n_links = 1;
98-
99- while ((counter = HeNEXT(counter)))
100- n_links++;
101-
102- if (n_links > HV_MAX_LENGTH_BEFORE_SPLIT) {
103- hsplit(hv);
104- }
105- }
106+ xhv->xhv_keys++; /* HvTOTALKEYS(hv)++ */
107+ if ( SHOULD_DO_HSPLIT(xhv) ) {
108+ hsplit(hv);
109 }
110
111 if (return_svp) {
112@@ -1192,7 +1173,7 @@ S_hsplit(pTHX_ HV *hv)
113
114
115 /* Pick your policy for "hashing isn't working" here: */
116- if (longest_chain <= HV_MAX_LENGTH_BEFORE_SPLIT /* split worked? */
117+ if (longest_chain <= HV_MAX_LENGTH_BEFORE_REHASH /* split worked? */
118 || HvREHASH(hv)) {
119 return;
120 }
121@@ -2831,8 +2812,8 @@ S_share_hek_flags(pTHX_ const char *str, I32 len, register U32 hash, int flags)
122
123 xhv->xhv_keys++; /* HvTOTALKEYS(hv)++ */
124 if (!next) { /* initial entry? */
125- } else if (xhv->xhv_keys > xhv->xhv_max /* HvKEYS(hv) > HvMAX(hv) */) {
126- hsplit(PL_strtab);
127+ } else if ( SHOULD_DO_HSPLIT(xhv) ) {
128+ hsplit(PL_strtab);
129 }
130 }
131
132diff --git a/t/op/hash.t b/t/op/hash.t
133index 278bea7..201260a 100644
134--- a/t/op/hash.t
135+++ b/t/op/hash.t
136@@ -39,22 +39,36 @@ use constant THRESHOLD => 14;
137 use constant START => "a";
138
139 # some initial hash data
140-my %h2 = map {$_ => 1} 'a'..'cc';
141+my %h2;
142+my $counter= "a";
143+$h2{$counter++}++ while $counter ne 'cd';
144
145 ok (!Internals::HvREHASH(%h2),
146 "starting with pre-populated non-pathological hash (rehash flag if off)");
147
148 my @keys = get_keys(\%h2);
149+my $buckets= buckets(\%h2);
150 $h2{$_}++ for @keys;
151+$h2{$counter++}++ while buckets(\%h2) == $buckets; # force a split
152 ok (Internals::HvREHASH(%h2),
153- scalar(@keys) . " colliding into the same bucket keys are triggering rehash");
154+ scalar(@keys) . " colliding into the same bucket keys are triggering rehash after split");
155+
156+# returns the number of buckets in a hash
157+sub buckets {
158+ my $hr = shift;
159+ my $keys_buckets= scalar(%$hr);
160+ if ($keys_buckets=~m!/([0-9]+)\z!) {
161+ return 0+$1;
162+ } else {
163+ return 8;
164+ }
165+}
166
167 sub get_keys {
168 my $hr = shift;
169
170 # the minimum of bits required to mount the attack on a hash
171 my $min_bits = log(THRESHOLD)/log(2);
172-
173 # if the hash has already been populated with a significant amount
174 # of entries the number of mask bits can be higher
175 my $keys = scalar keys %$hr;
176--
1771.8.3.1
178