Vulnerability CVE-2024-42106
Published: 2024-07-30

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

 References:
https://git.kernel.org/stable/c/7094a5fd20ab66028f1da7f06e0f2692d70346f9
https://git.kernel.org/stable/c/0184bf0a349f4cf9e663abbe862ff280e8e4dfa2
https://git.kernel.org/stable/c/7ef519c8efde152e0d632337f2994f6921e0b7e4
https://git.kernel.org/stable/c/8366720519ea8d322a20780debdfd23d9fc0904a
https://git.kernel.org/stable/c/d6f487e0704de2f2d15f8dd5d7d723210f2b2fdb
https://git.kernel.org/stable/c/76965648fe6858db7c5f3c700fef7aa5f124ca1c
https://git.kernel.org/stable/c/f9b2010e8af49fac9d9562146fb81744d8a9b051
https://git.kernel.org/stable/c/61cf1c739f08190a4cbf047b9fbb192a94d87e3f
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