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Avoid race condition in Regexp#match #4734

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Merged
merged 1 commit into from
Oct 2, 2021
Merged

Avoid race condition in Regexp#match #4734

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46 changes: 19 additions & 27 deletions re.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1534,8 +1534,8 @@ rb_reg_adjust_startpos(VALUE re, VALUE str, long pos, int reverse)
}

/* returns byte offset */
long
rb_reg_search0(VALUE re, VALUE str, long pos, int reverse, int set_backref_str)
static long
rb_reg_search_set_match(VALUE re, VALUE str, long pos, int reverse, int set_backref_str, VALUE *set_match)
{
long result;
VALUE match;
Expand All @@ -1557,18 +1557,7 @@ rb_reg_search0(VALUE re, VALUE str, long pos, int reverse, int set_backref_str)
tmpreg = reg != RREGEXP_PTR(re);
if (!tmpreg) RREGEXP(re)->usecnt++;

match = rb_backref_get();
if (!NIL_P(match)) {
if (FL_TEST(match, MATCH_BUSY)) {
match = Qnil;
}
else {
regs = RMATCH_REGS(match);
}
}
if (NIL_P(match)) {
MEMZERO(regs, struct re_registers, 1);
}
MEMZERO(regs, struct re_registers, 1);
if (!reverse) {
range += len;
}
Expand Down Expand Up @@ -1601,24 +1590,28 @@ rb_reg_search0(VALUE re, VALUE str, long pos, int reverse, int set_backref_str)
}
}

if (NIL_P(match)) {
int err;
match = match_alloc(rb_cMatch);
err = rb_reg_region_copy(RMATCH_REGS(match), regs);
onig_region_free(regs, 0);
if (err) rb_memerror();
}
match = match_alloc(rb_cMatch);
int copy_err = rb_reg_region_copy(RMATCH_REGS(match), regs);
onig_region_free(regs, 0);
if (copy_err) rb_memerror();

if (set_backref_str) {
RMATCH(match)->str = rb_str_new4(str);
}

RMATCH(match)->regexp = re;
rb_backref_set(match);
if (set_match) *set_match = match;

return result;
}

long
rb_reg_search0(VALUE re, VALUE str, long pos, int reverse, int set_backref_str)
{
return rb_reg_search_set_match(re, str, pos, reverse, set_backref_str, NULL);
}

long
rb_reg_search(VALUE re, VALUE str, long pos, int reverse)
{
Expand Down Expand Up @@ -3124,7 +3117,7 @@ reg_operand(VALUE s, int check)
}

static long
reg_match_pos(VALUE re, VALUE *strp, long pos)
reg_match_pos(VALUE re, VALUE *strp, long pos, VALUE* set_match)
{
VALUE str = *strp;

Expand All @@ -3143,7 +3136,7 @@ reg_match_pos(VALUE re, VALUE *strp, long pos)
}
pos = rb_str_offset(str, pos);
}
return rb_reg_search(re, str, pos, 0);
return rb_reg_search_set_match(re, str, pos, 0, 1, set_match);
}

/*
Expand Down Expand Up @@ -3197,7 +3190,7 @@ reg_match_pos(VALUE re, VALUE *strp, long pos)
VALUE
rb_reg_match(VALUE re, VALUE str)
{
long pos = reg_match_pos(re, &str, 0);
long pos = reg_match_pos(re, &str, 0, NULL);
if (pos < 0) return Qnil;
pos = rb_str_sublen(str, pos);
return LONG2FIX(pos);
Expand Down Expand Up @@ -3308,7 +3301,7 @@ rb_reg_match2(VALUE re)
static VALUE
rb_reg_match_m(int argc, VALUE *argv, VALUE re)
{
VALUE result, str, initpos;
VALUE result = Qnil, str, initpos;
long pos;

if (rb_scan_args(argc, argv, "11", &str, &initpos) == 2) {
Expand All @@ -3318,12 +3311,11 @@ rb_reg_match_m(int argc, VALUE *argv, VALUE re)
pos = 0;
}

pos = reg_match_pos(re, &str, pos);
pos = reg_match_pos(re, &str, pos, &result);
if (pos < 0) {
rb_backref_set(Qnil);
return Qnil;
}
result = rb_backref_get();
rb_match_busy(result);
if (!NIL_P(result) && rb_block_given_p()) {
return rb_yield(result);
Expand Down
21 changes: 21 additions & 0 deletions test/ruby/test_regexp.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -265,6 +265,27 @@ def test_match_regexp
assert_equal(re, re.match("foo").regexp)
end

def test_match_lambda_multithread
bug17507 = "[ruby-core:101901]"
str = "a-x-foo-bar-baz-z-b"

worker = lambda do
m = /foo-([A-Za-z0-9_\.]+)-baz/.match(str)
assert_equal("bar", m[1], bug17507)

# These two lines are needed to trigger the bug
File.exist? "/tmp"
str.gsub(/foo-bar-baz/, "foo-abc-baz")
end

def self. threaded_test(worker)
6.times.map {Thread.new {10_000.times {worker.call}}}.each(&:join)
end

# The bug only occurs in a method calling a block/proc/lambda
threaded_test(worker)
end

def test_source
bug5484 = '[ruby-core:40364]'
assert_equal('', //.source)
Expand Down