CVE: CVE-2024-50034
Published: 2024-10-21
Description: In the Linux kernel, the following vulnerability has been resolved:

net/smc: fix lacks of icsk_syn_mss with IPPROTO_SMC

Eric report a panic on IPPROTO_SMC, and give the facts
that when INET_PROTOSW_ICSK was set, icsk->icsk_sync_mss must be set too.

Bug: Unable to handle kernel NULL pointer dereference at virtual address
[PII_REDACTED]
Mem abort info:
ESR = 0x[PII_REDACTED]000005
EC = 0x21: IABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x05: level 1 translation fault
user pgtable: 4k pages, 48-bit VAs, pgdp=[PII_REDACTED]5d1000
[[PII_REDACTED]] pgd=[PII_REDACTED]c46003, p4d=[PII_REDACTED]c46003,
pud=[PII_REDACTED]
Internal error: Oops: [PII_REDACTED] [#1] PREEMPT SMP
Modules linked in:
CPU: 1 UID: 0 PID: 8037 Comm: syz.3.265 Not tainted
6.11.0-rc7-syzkaller-g5f[PII_REDACTED] #0
Hardware name: Google Google Compute Engine/Google Compute Engine,
BIOS Google 08/06/2024
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : 0x0
lr : cipso_v4_sock_setattr+0x2a8/0x3c0 net/ipv4/cipso_ipv4.c:1910
sp : ffff80009b887a90
x29: ffff80009b887aa0 x28: ffff80008db94050 x27: [PII_REDACTED]
x26: 1fffe0001aa6f5b3 x25: dfff[PII_REDACTED]00 x24: ffff0000db75da00
x23: [PII_REDACTED] x22: ffff0000d8b78518 x21: [PII_REDACTED]
x20: ffff0000d537ad80 x19: ffff0000d8b78000 x18: 1fffe000366d79ee
x17: ffff[PII_REDACTED]a8 x16: ffff800080569b84 x15: [PII_REDACTED]
x14: 000000008b336894 x13: 00000000cd96feaa x12: [PII_REDACTED]
x11: [PII_REDACTED] x10:[PII_REDACTED]0020a3 x9 : 1fffe0001b16f0f1
x8 : [PII_REDACTED] x7 : [PII_REDACTED] x6 :[PII_REDACTED]00003f
x5 : [PII_REDACTED] x4 : [PII_REDACTED] x3 : [PII_REDACTED]
x2 : [PII_REDACTED] x1 : [PII_REDACTED] x0 : ffff0000d8b78000
Call trace:
0x0
netlbl_sock_setattr+0x2e4/0x338 net/netlabel/netlabel_kapi.c:1000
smack_netlbl_add+0xa4/0x154 security/smack/smack_lsm.c:2593
smack_socket_post_create+0xa8/0x14c security/smack/smack_lsm.c:2973
security_socket_post_create+0x94/0xd4 security/security.c:4425
__sock_create+0x4c8/0x884 net/socket.c:1587
sock_create net/socket.c:1622 [inline]
__sys_socket_create net/socket.c:1659 [inline]
__sys_socket+0x134/0x340 net/socket.c:1706
__do_sys_socket net/socket.c:1720 [inline]
__se_sys_socket net/socket.c:1718 [inline]
__arm64_sys_socket+0x7c/0x94 net/socket.c:1718
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
Code: ???????? ???????? ???????? ???????? (????????)
---[ end trace [PII_REDACTED] ]---

This patch add a toy implementation that performs a simple return to
prevent such panic. This is because MSS can be set in sock_create_kern
or smc_setsockopt, similar to how it's done in AF_SMC. However, for
AF_SMC, there is currently no way to synchronize MSS within
__sys_connect_file. This toy implementation lays the groundwork for us
to support such feature for IPPROTO_SMC in the future.
CVSS Score: 5.5 (MEDIUM)
CWE: CWE-476
References: https://git.kernel.org/stable/c/44dc50df15f5bd4221d8f708885a9d49cda7f57e; https://git.kernel.org/stable/c/6fd27ea183c208e478129a85e11d880fc70040f2