[Python-checkins] bpo-9566: Fix compiler warnings in peephole.c (GH-10652)

Fri Dec 7 11:54:26 EST 2018

https://github.com/python/cpython/commit/028f0ef4f3111d2b3fc5b971642e337ba7990873
commit: 028f0ef4f3111d2b3fc5b971642e337ba7990873
branch: master
author: Victor Stinner <vstinner at redhat.com>
committer: GitHub <noreply at github.com>
date: 2018年12月07日T17:54:18+01:00
summary:
bpo-9566: Fix compiler warnings in peephole.c (GH-10652)
files:
M Python/peephole.c

diff --git a/Python/peephole.c b/Python/peephole.c
index 77d134939f8d..cc244aa433ee 100644
--- a/Python/peephole.c
+++ b/Python/peephole.c
@@ -152,6 +152,15 @@ fold_tuple_on_constants(_Py_CODEUNIT *codestr, Py_ssize_t codelen,
 PyTuple_SET_ITEM(newconst, i, constant);
 }
 
+ Py_ssize_t index = PyList_GET_SIZE(consts);
+#if SIZEOF_SIZE_T > SIZEOF_INT
+ if ((size_t)index >= UINT_MAX - 1) {
+ Py_DECREF(newconst);
+ PyErr_SetString(PyExc_OverflowError, "too many constants");
+ return -1;
+ }
+#endif
+
 /* Append folded constant onto consts */
 if (PyList_Append(consts, newconst)) {
 Py_DECREF(newconst);
@@ -160,7 +169,7 @@ fold_tuple_on_constants(_Py_CODEUNIT *codestr, Py_ssize_t codelen,
 Py_DECREF(newconst);
 
 return copy_op_arg(codestr, c_start, LOAD_CONST,
- PyList_GET_SIZE(consts)-1, opcode_end);
+ (unsigned int)index, opcode_end);
 }
 
 static unsigned int *
@@ -221,7 +230,7 @@ PyObject *
 PyCode_Optimize(PyObject *code, PyObject* consts, PyObject *names,
 PyObject *lnotab_obj)
 {
- Py_ssize_t h, i, nexti, op_start, codelen, tgt;
+ Py_ssize_t h, i, nexti, op_start, tgt;
 unsigned int j, nops;
 unsigned char opcode, nextop;
 _Py_CODEUNIT *codestr = NULL;
@@ -249,17 +258,22 @@ PyCode_Optimize(PyObject *code, PyObject* consts, PyObject *names,
 the peephole optimizer doesn't modify line numbers. */
 
 assert(PyBytes_Check(code));
- codelen = PyBytes_GET_SIZE(code);
- assert(codelen % sizeof(_Py_CODEUNIT) == 0);
+ Py_ssize_t codesize = PyBytes_GET_SIZE(code);
+ assert(codesize % sizeof(_Py_CODEUNIT) == 0);
+ Py_ssize_t codelen = codesize / sizeof(_Py_CODEUNIT);
+ if (codelen > INT_MAX) {
+ /* Python assembler is limited to INT_MAX: see assembler.a_offset in
+ compile.c. */
+ goto exitUnchanged;
+ }
 
 /* Make a modifiable copy of the code string */
- codestr = (_Py_CODEUNIT *)PyMem_Malloc(codelen);
+ codestr = (_Py_CODEUNIT *)PyMem_Malloc(codesize);
 if (codestr == NULL) {
 PyErr_NoMemory();
 goto exitError;
 }
- memcpy(codestr, PyBytes_AS_STRING(code), codelen);
- codelen /= sizeof(_Py_CODEUNIT);
+ memcpy(codestr, PyBytes_AS_STRING(code), codesize);
 
 blocks = markblocks(codestr, codelen);
 if (blocks == NULL)
@@ -357,7 +371,11 @@ PyCode_Optimize(PyObject *code, PyObject* consts, PyObject *names,
 jump past it), and all conditional jumps pop their
 argument when they're not taken (so change the
 first jump to pop its argument when it's taken). */
- h = set_arg(codestr, i, (tgt + 1) * sizeof(_Py_CODEUNIT));
+ Py_ssize_t arg = (tgt + 1);
+ /* cannot overflow: codelen <= INT_MAX */
+ assert((size_t)arg <= UINT_MAX / sizeof(_Py_CODEUNIT));
+ arg *= sizeof(_Py_CODEUNIT);
+ h = set_arg(codestr, i, (unsigned int)arg);
 j = opcode == JUMP_IF_TRUE_OR_POP ?
 POP_JUMP_IF_TRUE : POP_JUMP_IF_FALSE;
 }
@@ -383,17 +401,20 @@ PyCode_Optimize(PyObject *code, PyObject* consts, PyObject *names,
 codestr[op_start] = PACKOPARG(RETURN_VALUE, 0);
 fill_nops(codestr, op_start + 1, i + 1);
 } else if (UNCONDITIONAL_JUMP(_Py_OPCODE(codestr[tgt]))) {
- j = GETJUMPTGT(codestr, tgt);
+ size_t arg = GETJUMPTGT(codestr, tgt);
 if (opcode == JUMP_FORWARD) { /* JMP_ABS can go backwards */
 opcode = JUMP_ABSOLUTE;
 } else if (!ABSOLUTE_JUMP(opcode)) {
- if ((Py_ssize_t)j < i + 1) {
+ if (arg < (size_t)(i + 1)) {
 break; /* No backward relative jumps */
 }
- j -= i + 1; /* Calc relative jump addr */
+ arg -= i + 1; /* Calc relative jump addr */
 }
- j *= sizeof(_Py_CODEUNIT);
- copy_op_arg(codestr, op_start, opcode, j, i + 1);
+ /* cannot overflow: codelen <= INT_MAX */
+ assert(arg <= (UINT_MAX / sizeof(_Py_CODEUNIT)));
+ arg *= sizeof(_Py_CODEUNIT);
+ copy_op_arg(codestr, op_start, opcode,
+ (unsigned int)arg, i + 1);
 }
 break;
 
@@ -427,11 +448,14 @@ PyCode_Optimize(PyObject *code, PyObject* consts, PyObject *names,
 
 /* Fixup lnotab */
 for (i = 0, nops = 0; i < codelen; i++) {
- assert(i - nops <= INT_MAX);
+ size_t block = (size_t)i - nops;
+ /* cannot overflow: codelen <= INT_MAX */
+ assert(block <= UINT_MAX);
 /* original code offset => new code offset */
- blocks[i] = i - nops;
- if (_Py_OPCODE(codestr[i]) == NOP)
+ blocks[i] = (unsigned int)block;
+ if (_Py_OPCODE(codestr[i]) == NOP) {
 nops++;
+ }
 }
 cum_orig_offset = 0;
 last_offset = 0;
@@ -476,12 +500,14 @@ PyCode_Optimize(PyObject *code, PyObject* consts, PyObject *names,
 j *= sizeof(_Py_CODEUNIT);
 break;
 }
- nexti = i - op_start + 1;
- if (instrsize(j) > nexti)
+ Py_ssize_t ilen = i - op_start + 1;
+ if (instrsize(j) > ilen) {
 goto exitUnchanged;
- /* If instrsize(j) < nexti, we'll emit EXTENDED_ARG 0 */
- write_op_arg(codestr + h, opcode, j, nexti);
- h += nexti;
+ }
+ assert(ilen <= INT_MAX);
+ /* If instrsize(j) < ilen, we'll emit EXTENDED_ARG 0 */
+ write_op_arg(codestr + h, opcode, j, (int)ilen);
+ h += ilen;
 }
 assert(h + (Py_ssize_t)nops == codelen);
 
