Issue #28563: Fixed possible DoS and arbitrary code execution when handle

plural form selections in the gettext module.  The expression parser now
supports exact syntax supported by GNU gettext.

1 files changed, 84 insertions, 1 deletions

diff --git a/Lib/test/test_gettext.py b/Lib/test/test_gettext.py
index 5456948ca4..f8df62246e 100644
--- a/Lib/test/test_gettext.py
+++ b/Lib/test/test_gettext.py
@@ -230,7 +230,9 @@ class PluralFormsTestCase(GettextBaseTest):
         x = t.ngettext('There is %s file', 'There are %s files', 2)
         eq(x, 'Hay %s ficheros')
 
-    def test_hu(self):
+    # Examples from http://www.gnu.org/software/gettext/manual/gettext.html
+
+    def test_ja(self):
         eq = self.assertEqual
         f = gettext.c2py('0')
         s = ''.join([ str(f(x)) for x in range(200) ])
@@ -248,6 +250,12 @@ class PluralFormsTestCase(GettextBaseTest):
         s = ''.join([ str(f(x)) for x in range(200) ])
         eq(s, "00111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111")
 
+    def test_lv(self):
+        eq = self.assertEqual
+        f = gettext.c2py('n%10==1 && n%100!=11 ? 0 : n != 0 ? 1 : 2')
+        s = ''.join([ str(f(x)) for x in range(200) ])
+        eq(s, "20111111111111111111101111111110111111111011111111101111111110111111111011111111101111111110111111111011111111111111111110111111111011111111101111111110111111111011111111101111111110111111111011111111")
+
     def test_gd(self):
         eq = self.assertEqual
         f = gettext.c2py('n==1 ? 0 : n==2 ? 1 : 2')
@@ -261,6 +269,12 @@ class PluralFormsTestCase(GettextBaseTest):
         s = ''.join([ str(f(x)) for x in range(200) ])
         eq(s, "20122222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222")
 
+    def test_ro(self):
+        eq = self.assertEqual
+        f = gettext.c2py('n==1 ? 0 : (n==0 || (n%100 > 0 && n%100 < 20)) ? 1 : 2')
+        s = ''.join([ str(f(x)) for x in range(200) ])
+        eq(s, "10111111111111111111222222222222222222222222222222222222222222222222222222222222222222222222222222222111111111111111111122222222222222222222222222222222222222222222222222222222222222222222222222222222")
+
     def test_lt(self):
         eq = self.assertEqual
         f = gettext.c2py('n%10==1 && n%100!=11 ? 0 : n%10>=2 && (n%100<10 || n%100>=20) ? 1 : 2')
@@ -273,6 +287,12 @@ class PluralFormsTestCase(GettextBaseTest):
         s = ''.join([ str(f(x)) for x in range(200) ])
         eq(s, "20111222222222222222201112222220111222222011122222201112222220111222222011122222201112222220111222222011122222222222222220111222222011122222201112222220111222222011122222201112222220111222222011122222")
 
+    def test_cs(self):
+        eq = self.assertEqual
+        f = gettext.c2py('(n==1) ? 0 : (n>=2 && n<=4) ? 1 : 2')
+        s = ''.join([ str(f(x)) for x in range(200) ])
+        eq(s, "20111222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222")
+
     def test_pl(self):
         eq = self.assertEqual
         f = gettext.c2py('n==1 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2')
@@ -285,10 +305,73 @@ class PluralFormsTestCase(GettextBaseTest):
         s = ''.join([ str(f(x)) for x in range(200) ])
         eq(s, "30122333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333012233333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333")
 
+    def test_ar(self):
+        eq = self.assertEqual
+        f = gettext.c2py('n==0 ? 0 : n==1 ? 1 : n==2 ? 2 : n%100>=3 && n%100<=10 ? 3 : n%100>=11 ? 4 : 5')
+        s = ''.join([ str(f(x)) for x in range(200) ])
+        eq(s, "01233333333444444444444444444444444444444444444444444444444444444444444444444444444444444444444444445553333333344444444444444444444444444444444444444444444444444444444444444444444444444444444444444444")
+
     def test_security(self):
         raises = self.assertRaises
         # Test for a dangerous expression
         raises(ValueError, gettext.c2py, "os.chmod('/etc/passwd',0777)")
+        # issue28563
+        raises(ValueError, gettext.c2py, '"(eval(foo) && ""')
+        raises(ValueError, gettext.c2py, 'f"{os.system(\'sh\')}"')
+        # Maximum recursion depth exceeded during compilation
+        raises(ValueError, gettext.c2py, 'n+'*10000 + 'n')
+        self.assertEqual(gettext.c2py('n+'*100 + 'n')(1), 101)
+        # MemoryError during compilation
+        raises(ValueError, gettext.c2py, '('*100 + 'n' + ')'*100)
+        # Maximum recursion depth exceeded in C to Python translator
+        raises(ValueError, gettext.c2py, '('*10000 + 'n' + ')'*10000)
+        self.assertEqual(gettext.c2py('('*20 + 'n' + ')'*20)(1), 1)
+
+    def test_chained_comparison(self):
+        # C doesn't chain comparison as Python so 2 == 2 == 2 gets different results
+        f = gettext.c2py('n == n == n')
+        self.assertEqual(''.join(str(f(x)) for x in range(3)), '010')
+        f = gettext.c2py('1 < n == n')
+        self.assertEqual(''.join(str(f(x)) for x in range(3)), '100')
+        f = gettext.c2py('n == n < 2')
+        self.assertEqual(''.join(str(f(x)) for x in range(3)), '010')
+        f = gettext.c2py('0 < n < 2')
+        self.assertEqual(''.join(str(f(x)) for x in range(3)), '111')
+
+    def test_decimal_number(self):
+        self.assertEqual(gettext.c2py('0123')(1), 123)
+
+    def test_invalid_syntax(self):
+        invalid_expressions = [
+            'x>1', '(n>1', 'n>1)', '42**42**42', '0xa', '1.0', '1e2',
+            'n>0x1', '+n', '-n', 'n()', 'n(1)', '1+', 'nn', 'n n',
+        ]
+        for expr in invalid_expressions:
+            with self.assertRaises(ValueError):
+                gettext.c2py(expr)
+
+    def test_nested_condition_operator(self):
+        self.assertEqual(gettext.c2py('n?1?2:3:4')(0), 4)
+        self.assertEqual(gettext.c2py('n?1?2:3:4')(1), 2)
+        self.assertEqual(gettext.c2py('n?1:3?4:5')(0), 4)
+        self.assertEqual(gettext.c2py('n?1:3?4:5')(1), 1)
+
+    def test_division(self):
+        f = gettext.c2py('2/n*3')
+        self.assertEqual(f(1), 6)
+        self.assertEqual(f(2), 3)
+        self.assertEqual(f(3), 0)
+        self.assertEqual(f(-1), -6)
+        self.assertRaises(ZeroDivisionError, f, 0)
+
+    def test_plural_number(self):
+        f = gettext.c2py('1')
+        self.assertEqual(f(1), 1)
+        self.assertRaises(ValueError, f, 1.0)
+        self.assertRaises(ValueError, f, '1')
+        self.assertRaises(ValueError, f, [])
+        self.assertRaises(ValueError, f, object())
+
 
 
 class UnicodeTranslationsTest(GettextBaseTest):