8000 [3.7] bpo-24618: Add a check in the code constructor. (GH-8283) by miss-islington · Pull Request #8291 · python/cpython · GitHub
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[3.7] bpo-24618: Add a check in the code constructor. (GH-8283) #8291

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Merged
merged 1 commit into from
Jul 16, 2018
Merged

[3.7] bpo-24618: Add a check in the code constructor. (GH-8283) #8291

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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2018-07-14-14-01-37.bpo-24618.iTKjD_.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fixed reading invalid memory when create the code object with too small
varnames tuple or too large argument counts.
18 changes: 15 additions & 3 deletions Objects/codeobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -103,7 +103,7 @@ PyCode_New(int argcount, int kwonlyargcount,
{
PyCodeObject *co;
Py_ssize_t *cell2arg = NULL;
Py_ssize_t i, n_cellvars;
Py_ssize_t i, n_cellvars, n_varnames, total_args;

/* Check argument types */
if (argcount < 0 || kwonlyargcount < 0 || nlocals < 0 ||
Expand Down Expand Up @@ -138,10 +138,22 @@ PyCode_New(int argcount, int kwonlyargcount,
flags &= ~CO_NOFREE;
}

n_varnames = PyTuple_GET_SIZE(varnames);
if (argcount <= n_varnames && kwonlyargcount <= n_varnames) {
/* Never overflows. */
total_args = (Py_ssize_t)argcount + (Py_ssize_t)kwonlyargcount +
((flags & CO_VARARGS) != 0) + ((flags & CO_VARKEYWORDS) != 0);
}
else {
total_args = n_varnames + 1;
}
if (total_args > n_varnames) {
PyErr_SetString(PyExc_ValueError, "code: varnames is too small");
return NULL;
}

/* Create mapping between cells and arguments if needed. */
if (n_cellvars) {
Py_ssize_t total_args = argcount + kwonlyargcount +
((flags & CO_VARARGS) != 0) + ((flags & CO_VARKEYWORDS) != 0);
bool used_cell2arg = false;
cell2arg = PyMem_NEW(Py_ssize_t, n_cellvars);
if (cell2arg == NULL) {
Expand Down
0