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fix up signedness in PyImport_ExtendInittab (#4831)

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As a result of 92a3c6f493, the compiler complains:

Python/import.c:2311:21: warning: comparison of integers of different signs: 'long' and 'unsigned long' [-Wsign-compare]
    if ((i + n + 1) <= PY_SSIZE_T_MAX / sizeof(struct _inittab)) {
         ~~~~~~~~~  ^  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This overflow is extremely unlikely to happen, but let's avoid undefined
behavior anyway.
This commit is contained in:
Benjamin Peterson 2017-12-15 23:42:33 -08:00 • committed by GitHub
parent 9454060e84
commit 0c644fcda0
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GPG key ID: 4AEE18F83AFDEB23
1 changed files with 3 additions and 5 deletions
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8
Python/import.c
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@ -2291,7 +2291,7 @@ int
PyImport_ExtendInittab(struct _inittab *newtab) PyImport_ExtendInittab(struct _inittab *newtab)
{ {
struct _inittab *p; struct _inittab *p;
Py_ssize_t i, n; size_t i, n;
int res = 0; int res = 0;
/* Count the number of entries in both tables */ /* Count the number of entries in both tables */
@ -2308,13 +2308,11 @@ PyImport_ExtendInittab(struct _inittab *newtab)
_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc); _PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
/* Allocate new memory for the combined table */ /* Allocate new memory for the combined table */
if ((i + n + 1) <= PY_SSIZE_T_MAX / (Py_ssize_t)sizeof(struct _inittab)) { p = NULL;
if (i + n <= SIZE_MAX / sizeof(struct _inittab) - 1) {
size_t size = sizeof(struct _inittab) * (i + n + 1); size_t size = sizeof(struct _inittab) * (i + n + 1);
p = PyMem_RawRealloc(inittab_copy, size); p = PyMem_RawRealloc(inittab_copy, size);
} }
else {
p = NULL;
}
if (p == NULL) { if (p == NULL) {
res = -1; res = -1;
goto done; goto done;