From 22bbb0c4c7ba4cfddea3f4cec03f50be34479516 Mon Sep 17 00:00:00 2001 From: Serhiy Storchaka Date: Thu, 3 Nov 2022 12:18:50 +0200 Subject: [PATCH] [3.10] gh-98740: Fix validation of conditional expressions in RE (GH-98764) (GH-99046) In very rare circumstances the JUMP opcode could be confused with the argument of the opcode in the "then" part which doesn't end with the JUMP opcode. This led to incorrect detection of the final JUMP opcode and incorrect calculation of the size of the subexpression. NOTE: Changed return value of functions _validate_inner() and _validate_charset() in Modules/_sre/sre.c. Now they return 0 on success, -1 on failure, and 1 if the last op is JUMP (which usually is a failure). Previously they returned 1 on success and 0 on failure. (cherry picked from commit e9ac890c0273aee413aa528cc202c3efa29f1d7a) Co-authored-by: Serhiy Storchaka --- Doc/library/re.rst | 3 ++ Lib/test/test_re.py | 5 ++ ...2-10-27-12-56-38.gh-issue-98740.ZoqqGM.rst | 3 ++ Modules/_sre.c | 54 ++++++++++--------- 4 files changed, 39 insertions(+), 26 deletions(-) create mode 100644 Misc/NEWS.d/next/Library/2022-10-27-12-56-38.gh-issue-98740.ZoqqGM.rst diff --git a/Doc/library/re.rst b/Doc/library/re.rst index e7d1f0560b2a..40e2dccaae3f 100644 --- a/Doc/library/re.rst +++ b/Doc/library/re.rst @@ -421,6 +421,9 @@ The special characters are: some fixed length. Patterns which start with negative lookbehind assertions may match at the beginning of the string being searched. +.. _re-conditional-expression: +.. index:: single: (?(; in regular expressions + ``(?(id/name)yes-pattern|no-pattern)`` Will try to match with ``yes-pattern`` if the group with given *id* or *name* exists, and with ``no-pattern`` if it doesn't. ``no-pattern`` is diff --git a/Lib/test/test_re.py b/Lib/test/test_re.py index 62bfc3a7aa43..010c52e75c91 100644 --- a/Lib/test/test_re.py +++ b/Lib/test/test_re.py @@ -578,6 +578,11 @@ class ReTests(unittest.TestCase): self.checkPatternError(r'()(?(2)a)', "invalid group reference 2", 5) + def test_re_groupref_exists_validation_bug(self): + for i in range(256): + with self.subTest(code=i): + re.compile(r'()(?(1)\x%02x?)' % i) + def test_re_groupref_overflow(self): from sre_constants import MAXGROUPS self.checkTemplateError('()', r'\g<%s>' % MAXGROUPS, 'xx', diff --git a/Misc/NEWS.d/next/Library/2022-10-27-12-56-38.gh-issue-98740.ZoqqGM.rst b/Misc/NEWS.d/next/Library/2022-10-27-12-56-38.gh-issue-98740.ZoqqGM.rst new file mode 100644 index 000000000000..887d506d4bdd --- /dev/null +++ b/Misc/NEWS.d/next/Library/2022-10-27-12-56-38.gh-issue-98740.ZoqqGM.rst @@ -0,0 +1,3 @@ +Fix internal error in the :mod:`re` module which in very rare circumstances +prevented compilation of a regular expression containing a :ref:`conditional +expression ` without the "else" branch. diff --git a/Modules/_sre.c b/Modules/_sre.c index 911626dafc97..2dfbf854db0d 100644 --- a/Modules/_sre.c +++ b/Modules/_sre.c @@ -1519,7 +1519,7 @@ _sre_compile_impl(PyObject *module, PyObject *pattern, int flags, #endif /* Report failure */ -#define FAIL do { VTRACE(("FAIL: %d\n", __LINE__)); return 0; } while (0) +#define FAIL do { VTRACE(("FAIL: %d\n", __LINE__)); return -1; } while (0) /* Extract opcode, argument, or skip count from code array */ #define GET_OP \ @@ -1543,7 +1543,7 @@ _sre_compile_impl(PyObject *module, PyObject *pattern, int flags, skip = *code; \ VTRACE(("%lu (skip to %p)\n", \ (unsigned long)skip, code+skip)); \ - if (skip-adj > (uintptr_t)(end - code)) \ + if (skip-adj > (uintptr_t)(end - code)) \ FAIL; \ code++; \ } while (0) @@ -1632,9 +1632,10 @@ _validate_charset(SRE_CODE *code, SRE_CODE *end) } } - return 1; + return 0; } +/* Returns 0 on success, -1 on failure, and 1 if the last op is JUMP. */ static int _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups) { @@ -1712,7 +1713,7 @@ _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups) case SRE_OP_IN_LOC_IGNORE: GET_SKIP; /* Stop 1 before the end; we check the FAILURE below */ - if (!_validate_charset(code, code+skip-2)) + if (_validate_charset(code, code+skip-2)) FAIL; if (code[skip-2] != SRE_OP_FAILURE) FAIL; @@ -1766,7 +1767,7 @@ _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups) } /* Validate the charset */ if (flags & SRE_INFO_CHARSET) { - if (!_validate_charset(code, newcode-1)) + if (_validate_charset(code, newcode-1)) FAIL; if (newcode[-1] != SRE_OP_FAILURE) FAIL; @@ -1787,7 +1788,7 @@ _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups) if (skip == 0) break; /* Stop 2 before the end; we check the JUMP below */ - if (!_validate_inner(code, code+skip-3, groups)) + if (_validate_inner(code, code+skip-3, groups)) FAIL; code += skip-3; /* Check that it ends with a JUMP, and that each JUMP @@ -1801,6 +1802,8 @@ _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups) else if (code+skip-1 != target) FAIL; } + if (code != target) + FAIL; } break; @@ -1815,7 +1818,7 @@ _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups) FAIL; if (max > SRE_MAXREPEAT) FAIL; - if (!_validate_inner(code, code+skip-4, groups)) + if (_validate_inner(code, code+skip-4, groups)) FAIL; code += skip-4; GET_OP; @@ -1834,7 +1837,7 @@ _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups) FAIL; if (max > SRE_MAXREPEAT) FAIL; - if (!_validate_inner(code, code+skip-3, groups)) + if (_validate_inner(code, code+skip-3, groups)) FAIL; code += skip-3; GET_OP; @@ -1886,24 +1889,17 @@ _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups) to allow arbitrary jumps anywhere in the code; so we just look for a JUMP opcode preceding our skip target. */ - if (skip >= 3 && skip-3 < (uintptr_t)(end - code) && - code[skip-3] == SRE_OP_JUMP) - { - VTRACE(("both then and else parts present\n")); - if (!_validate_inner(code+1, code+skip-3, groups)) - FAIL; + VTRACE(("then part:\n")); + int rc = _validate_inner(code+1, code+skip-1, groups); + if (rc == 1) { + VTRACE(("else part:\n")); code += skip-2; /* Position after JUMP, at */ GET_SKIP; - if (!_validate_inner(code, code+skip-1, groups)) - FAIL; - code += skip-1; - } - else { - VTRACE(("only a then part present\n")); - if (!_validate_inner(code+1, code+skip-1, groups)) - FAIL; - code += skip-1; + rc = _validate_inner(code, code+skip-1, groups); } + if (rc) + FAIL; + code += skip-1; break; case SRE_OP_ASSERT: @@ -1914,7 +1910,7 @@ _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups) if (arg & 0x80000000) FAIL; /* Width too large */ /* Stop 1 before the end; we check the SUCCESS below */ - if (!_validate_inner(code+1, code+skip-2, groups)) + if (_validate_inner(code+1, code+skip-2, groups)) FAIL; code += skip-2; GET_OP; @@ -1922,6 +1918,12 @@ _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups) FAIL; break; + case SRE_OP_JUMP: + if (code + 1 != end) + FAIL; + VTRACE(("JUMP: %d\n", __LINE__)); + return 1; + default: FAIL; @@ -1929,7 +1931,7 @@ _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups) } VTRACE(("okay\n")); - return 1; + return 0; } static int @@ -1944,7 +1946,7 @@ _validate_outer(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups) static int _validate(PatternObject *self) { - if (!_validate_outer(self->code, self->code+self->codesize, self->groups)) + if (_validate_outer(self->code, self->code+self->codesize, self->groups)) { PyErr_SetString(PyExc_RuntimeError, "invalid SRE code"); return 0; -- 2.47.3