[Python-checkins] bpo-45228: Fix stack buffer overflow in parsing J1939 address (GH-28404)

[miss-islington]

https://github.com/python/cpython/commit/98fef200bbfd8adec27799265deb200ab5e4513e
commit: 98fef200bbfd8adec27799265deb200ab5e4513e
branch: 3.9
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: miss-islington <31488909+miss-islington at users.noreply.github.com>
date: 2021-09-17T02:10:55-07:00
summary:

bpo-45228: Fix stack buffer overflow in parsing J1939 address (GH-28404)

(cherry picked from commit 773319545ba60577bc140aa46eac83b360240b7a)

Co-authored-by: Serhiy Storchaka <storchaka at gmail.com>

files:
A Misc/NEWS.d/next/Library/2021-09-17-09-59-33.bpo-45228.WV1dcT.rst
M Modules/socketmodule.c

diff --git a/Misc/NEWS.d/next/Library/2021-09-17-09-59-33.bpo-45228.WV1dcT.rst b/Misc/NEWS.d/next/Library/2021-09-17-09-59-33.bpo-45228.WV1dcT.rst
new file mode 100644
index 0000000000000..9336c0aed92bc
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-09-17-09-59-33.bpo-45228.WV1dcT.rst
@@ -0,0 +1 @@
+Fix stack buffer overflow in parsing J1939 network address.
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index dcb11ef62053a..0ac7fd0a607a0 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -1555,10 +1555,10 @@ makesockaddr(SOCKET_T sockfd, struct sockaddr *addr, size_t addrlen, int proto)
 #ifdef CAN_J1939
           case CAN_J1939:
           {
-              return Py_BuildValue("O&KkB", PyUnicode_DecodeFSDefault,
+              return Py_BuildValue("O&KIB", PyUnicode_DecodeFSDefault,
                                           ifname,
-                                          a->can_addr.j1939.name,
-                                          a->can_addr.j1939.pgn,
+                                          (unsigned long long)a->can_addr.j1939.name,
+                                          (unsigned int)a->can_addr.j1939.pgn,
                                           a->can_addr.j1939.addr);
           }
 #endif /* CAN_J1939 */
@@ -2249,13 +2249,13 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
             PyObject *interfaceName;
             struct ifreq ifr;
             Py_ssize_t len;
-            uint64_t j1939_name;
-            uint32_t j1939_pgn;
+            unsigned long long j1939_name; /* at least 64 bits */
+            unsigned int j1939_pgn; /* at least 32 bits */
             uint8_t j1939_addr;
 
             struct sockaddr_can *addr = &addrbuf->can;
 
-            if (!PyArg_ParseTuple(args, "O&KkB", PyUnicode_FSConverter,
+            if (!PyArg_ParseTuple(args, "O&KIB", PyUnicode_FSConverter,
                                               &interfaceName,
                                               &j1939_name,
                                               &j1939_pgn,
@@ -2283,8 +2283,8 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 
             addr->can_family = AF_CAN;
             addr->can_ifindex = ifr.ifr_ifindex;
-            addr->can_addr.j1939.name = j1939_name;
-            addr->can_addr.j1939.pgn = j1939_pgn;
+            addr->can_addr.j1939.name = (uint64_t)j1939_name;
+            addr->can_addr.j1939.pgn = (uint32_t)j1939_pgn;
             addr->can_addr.j1939.addr = j1939_addr;
 
             *len_ret = sizeof(*addr);