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gh-104432: Use `memcpy()` to avoid misaligned loads (#104433) 

Fix potential unaligned memory access on C APIs involving returned sequences
of `char *` pointers within the :mod:`grp` and :mod:`socket` modules. These
were revealed using a ``-fsaniziter=alignment`` build on ARM macOS.
This commit is contained in:
Christopher Chavez 2023-07-27 14:20:25 -05:00 committed by GitHub
parent 983305268e
commit f01e4cedba
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 29 additions and 7 deletions
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4
Misc/NEWS.d/next/Core and Builtins/2023-07-27-11-47-29.gh-issue-104432.oGHF-z.rst Normal file
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@ -0,0 +1,4 @@
Fix potential unaligned memory access on C APIs involving returned sequences
of `char *` pointers within the :mod:`grp` and :mod:`socket` modules. These
were revealed using a ``-fsaniziter=alignment`` build on ARM macOS. Patch by
Christopher Chavez.

10
Modules/grpmodule.c
View File

@ -65,8 +65,14 @@ mkgrent(PyObject *module, struct group *p)
Py_DECREF(v);
return NULL;
}
for (member = p->gr_mem; *member != NULL; member++) {
PyObject *x = PyUnicode_DecodeFSDefault(*member);
for (member = p->gr_mem; ; member++) {
char *group_member;
// member can be misaligned
memcpy(&group_member, member, sizeof(group_member));
if (group_member == NULL) {
break;
}
PyObject *x = PyUnicode_DecodeFSDefault(group_member);
if (x == NULL || PyList_Append(w, x) != 0) {
Py_XDECREF(x);
Py_DECREF(w);

22
Modules/socketmodule.c
View File

@ -5779,9 +5779,15 @@ gethost_common(socket_state *state, struct hostent *h, struct sockaddr *addr,
/* SF #1511317: h_aliases can be NULL */
if (h->h_aliases) {
for (pch = h->h_aliases; *pch != NULL; pch++) {
for (pch = h->h_aliases; ; pch++) {
int status;
tmp = PyUnicode_FromString(*pch);
char *host_alias;
// pch can be misaligned
memcpy(&host_alias, pch, sizeof(host_alias));
if (host_alias == NULL) {
break;
}
tmp = PyUnicode_FromString(host_alias);
if (tmp == NULL)
goto err;
@ -5793,8 +5799,14 @@ gethost_common(socket_state *state, struct hostent *h, struct sockaddr *addr,
}
}
for (pch = h->h_addr_list; *pch != NULL; pch++) {
for (pch = h->h_addr_list; ; pch++) {
int status;
char *host_address;
// pch can be misaligned
memcpy(&host_address, pch, sizeof(host_address));
if (host_address == NULL) {
break;
}
switch (af) {
@ -5806,7 +5818,7 @@ gethost_common(socket_state *state, struct hostent *h, struct sockaddr *addr,
#ifdef HAVE_SOCKADDR_SA_LEN
sin.sin_len = sizeof(sin);
#endif
memcpy(&sin.sin_addr, *pch, sizeof(sin.sin_addr));
memcpy(&sin.sin_addr, host_address, sizeof(sin.sin_addr));
tmp = make_ipv4_addr(&sin);
if (pch == h->h_addr_list && alen >= sizeof(sin))
@ -5823,7 +5835,7 @@ gethost_common(socket_state *state, struct hostent *h, struct sockaddr *addr,
#ifdef HAVE_SOCKADDR_SA_LEN
sin6.sin6_len = sizeof(sin6);
#endif
memcpy(&sin6.sin6_addr, *pch, sizeof(sin6.sin6_addr));
memcpy(&sin6.sin6_addr, host_address, sizeof(sin6.sin6_addr));
tmp = make_ipv6_addr(&sin6);
if (pch == h->h_addr_list && alen >= sizeof(sin6))