[Python-checkins] gh-104432: Use `memcpy()` to avoid misaligned loads (#104433)
gpshead
webhook-mailer at python.org
Thu Jul 27 15:20:29 EDT 2023
https://github.com/python/cpython/commit/f01e4cedba1a17d321664834bb255d9d04ad16ce
commit: f01e4cedba1a17d321664834bb255d9d04ad16ce
branch: main
author: Christopher Chavez <chrischavez at gmx.us>
committer: gpshead <greg at krypto.org>
date: 2023-07-27T19:20:25Z
summary:
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.
files:
A Misc/NEWS.d/next/Core and Builtins/2023-07-27-11-47-29.gh-issue-104432.oGHF-z.rst
M Modules/grpmodule.c
M Modules/socketmodule.c
diff --git a/Misc/NEWS.d/next/Core and Builtins/2023-07-27-11-47-29.gh-issue-104432.oGHF-z.rst b/Misc/NEWS.d/next/Core and Builtins/2023-07-27-11-47-29.gh-issue-104432.oGHF-z.rst
new file mode 100644
index 0000000000000..e47927b4e1188
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2023-07-27-11-47-29.gh-issue-104432.oGHF-z.rst
@@ -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.
diff --git a/Modules/grpmodule.c b/Modules/grpmodule.c
index 57cdde6064c24..f5709296334a8 100644
--- a/Modules/grpmodule.c
+++ b/Modules/grpmodule.c
@@ -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);
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index fc6a7f994bfd7..bb5edc368decb 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -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))
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