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Use a loop to strictly parse binary comparisons to avoid recursion (#892)

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Using recursion allows a malicious template to cause a SystemStackError
This commit is contained in:
Dylan Thacker-Smith
2017-05-10 10:41:52 -04:00
committed by GitHub
parent 8928454e29
commit 62d4625468
1 changed files with 8 additions and 5 deletions
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13
lib/liquid/tags/if.rb
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@@ -83,17 +83,20 @@ module Liquid
def strict_parse(markup)
p = Parser.new(markup)
condition = parse_binary_comparison(p)
condition = parse_binary_comparisons(p)
p.consume(:end_of_string)
condition
end
def parse_binary_comparison(p)
def parse_binary_comparisons(p)
condition = parse_comparison(p)
if op = (p.id?('and'.freeze) || p.id?('or'.freeze))
condition.send(op, parse_binary_comparison(p))
first_condition = condition
while op = (p.id?('and'.freeze) || p.id?('or'.freeze))
child_condition = parse_comparison(p)
condition.send(op, child_condition)
condition = child_condition
end
condition
first_condition
end
def parse_comparison(p)