CVE-2024-42106 (Moderate severity, published 2024-07-29)
CVSS score: 4.4 (CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H)
CWE: CWE-908
Description: In the Linux kernel, the following vulnerability has been resolved:

inet_diag: Initialize pad field in struct inet_diag_req_v2

KMSAN reported uninit-value access in raw_lookup() [1]. Diag for raw
sockets uses the pad field in struct inet_diag_req_v2 for the
underlying protocol. This field corresponds to the sdiag_raw_protocol
field in struct inet_diag_req_raw.

inet_diag_get_exact_compat() converts inet_diag_req to
inet_diag_req_v2, but leaves the pad field uninitialized. So the issue
occurs when raw_lookup() accesses the sdiag_raw_protocol field.

Fix this by initializing the pad field in
inet_diag_get_exact_compat(). Also, do the same fix in
inet_diag_dump_compat() to avoid the similar issue in the future.

[1]
BUG: KMSAN: uninit-value in raw_lookup net/ipv4/raw_diag.c:49 [inline]
BUG: KMSAN: uninit-value in raw_sock_get+0x657/0x800 net/ipv4/raw_diag.c:71
 raw_lookup net/ipv4/raw_diag.c:49 [inline]
 raw_sock_get+0x657/0x800 net/ipv4/raw_diag.c:71
 raw_diag_dump_one+0xa1/0x660 net/ipv4/raw_diag.c:99
 inet_diag_cmd_exact+0x7d9/0x980
 inet_diag_get_exact_compat net/ipv4/inet_diag.c:1404 [inline]
 inet_diag_rcv_msg_compat+0x469/0x530 net/ipv4/inet_diag.c:1426
 sock_diag_rcv_msg+0x23d/0x740 net/core/sock_diag.c:282
 netlink_rcv_skb+0x537/0x670 net/netlink/af_netlink.c:2564
 sock_diag_rcv+0x35/0x40 net/core/sock_diag.c:297
 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
 netlink_unicast+0xe74/0x1240 net/netlink/af_netlink.c:1361
 netlink_sendmsg+0x10c6/0x1260 net/netlink/af_netlink.c:1905
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x332/0x3d0 net/socket.c:745
 ____sys_sendmsg+0x7f0/0xb70 net/socket.c:2585
 ___sys_sendmsg+0x271/0x3b0 net/socket.c:2639
 __sys_sendmsg net/socket.c:2668 [inline]
 __do_sys_sendmsg net/socket.c:2677 [inline]
 __se_sys_sendmsg net/socket.c:2675 [inline]
 __x64_sys_sendmsg+0x27e/0x4a0 net/socket.c:2675
 x64_sys_call+0x135e/0x3ce0 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xd9/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
 raw_sock_get+0x650/0x800 net/ipv4/raw_diag.c:71
 raw_diag_dump_one+0xa1/0x660 net/ipv4/raw_diag.c:99
 inet_diag_cmd_exact+0x7d9/0x980
 inet_diag_get_exact_compat net/ipv4/inet_diag.c:1404 [inline]
 inet_diag_rcv_msg_compat+0x469/0x530 net/ipv4/inet_diag.c:1426
 sock_diag_rcv_msg+0x23d/0x740 net/core/sock_diag.c:282
 netlink_rcv_skb+0x537/0x670 net/netlink/af_netlink.c:2564
 sock_diag_rcv+0x35/0x40 net/core/sock_diag.c:297
 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
 netlink_unicast+0xe74/0x1240 net/netlink/af_netlink.c:1361
 netlink_sendmsg+0x10c6/0x1260 net/netlink/af_netlink.c:1905
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x332/0x3d0 net/socket.c:745
 ____sys_sendmsg+0x7f0/0xb70 net/socket.c:2585
 ___sys_sendmsg+0x271/0x3b0 net/socket.c:2639
 __sys_sendmsg net/socket.c:2668 [inline]
 __do_sys_sendmsg net/socket.c:2677 [inline]
 __se_sys_sendmsg net/socket.c:2675 [inline]
 __x64_sys_sendmsg+0x27e/0x4a0 net/socket.c:2675
 x64_sys_call+0x135e/0x3ce0 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xd9/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Local variable req.i created at:
 inet_diag_get_exact_compat net/ipv4/inet_diag.c:1396 [inline]
 inet_diag_rcv_msg_compat+0x2a6/0x530 net/ipv4/inet_diag.c:1426
 sock_diag_rcv_msg+0x23d/0x740 net/core/sock_diag.c:282

CPU: 1 PID: 8888 Comm: syz-executor.6 Not tainted 6.10.0-rc4-00217-g35bb670d65fc #32
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014
Mitigation: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.