8000 Fix ReDoS caused by very large character references using repeated 0s by Watson1978 · Pull Request #169 · ruby/rexml · GitHub
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Fix ReDoS caused by very large character references using repeated 0s #169

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Merged
merged 3 commits into from
Jul 16, 2024
Merged

Fix ReDoS caused by very large character references using repeated 0s #169

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bb274bc
Fix ReDoS caused by very large character references using repeated 0s
Watson1978 Jul 11, 2024
a2a8fb1
Update test
Watson1978 Jul 16, 2024
6d33f1d
Improve test name
kou Jul 16, 2024
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48 changes: 34 additions & 14 deletions lib/rexml/text.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -151,25 +151,45 @@ def Text.check string, pattern, doctype
end
end

# context sensitive
string.scan(pattern) do
if $1[-1] != ?;
raise "Illegal character #{$1.inspect} in raw string #{string.inspect}"
elsif $1[0] == ?&
if $5 and $5[0] == ?#
case ($5[1] == ?x ? $5[2..-1].to_i(16) : $5[1..-1].to_i)
when *VALID_CHAR
pos = 0
while (index = string.index(/<|&/, pos))
if string[index] == "<"
raise "Illegal character \"#{string[index]}\" in raw string #{string.inspect}"
end

unless (end_index = string.index(/[^\s];/, index + 1))
raise "Illegal character \"#{string[index]}\" in raw string #{string.inspect}"
end

value = string[(index + 1)..end_index]
if /\s/.match?(value)
raise "Illegal character \"#{string[index]}\" in raw string #{string.inspect}"
end

if value[0] == "#"
character_reference = value[1..-1]

unless (/\A(\d+|x[0-9a-fA-F]+)\z/.match?(character_reference))
if character_reference[0] == "x" || character_reference[-1] == "x"
raise "Illegal character \"#{string[index]}\" in raw string #{string.inspect}"
else
raise "Illegal character #{$1.inspect} in raw string #{string.inspect}"
raise "Illegal character #{string.inspect} in raw string #{string.inspect}"
end
# FIXME: below can't work but this needs API change.
# elsif @parent and $3 and !SUBSTITUTES.include?($1)
# if !doctype or !doctype.entities.has_key?($3)
# raise "Undeclared entity '#{$1}' in raw string \"#{string}\""
# end
end

case (character_reference[0] == "x" ? character_reference[1..-1].to_i(16) : character_reference[0..-1].to_i)
when *VALID_CHAR
else
raise "Illegal character #{string.inspect} in raw string #{string.inspect}"
end
elsif !(/\A#{Entity::NAME}\z/um.match?(value))
raise "Illegal character \"#{string[index]}\" in raw string #{string.inspect}"
end

pos = end_index + 1
end

string
end

def node_type
Expand Down
17 changes: 17 additions & 0 deletions test/parse/test_character_reference.rb
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Original file line number Diff line number Diff line change
@@ -0,0 +1,17 @@
require "test/unit"
require "core_assertions"

require "rexml/document"

module REXMLTests
class TestParseCharacterReference < Test::Unit::TestCase
include Test::Unit::CoreAssertions

def test_gt_linear_performance_many_preceding_zeros
seq = [10000, 50000, 100000, 150000, 200000]
assert_linear_performance(seq, rehearsal: 10) do |n|
REXML::Document.new('<test testing="&#' + "0" * n + '97;"/>')
end
end
end
end
0