CVE-2022-48751

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

net/smc: Transitional solution for clcsock race issue

We encountered a crash in smc_setsockopt() and it is caused by

accessing smc->clcsock after clcsock was released.

BUG: kernel NULL pointer dereference, address: 0000000000000020

#PF: supervisor read access in kernel mode

#PF: error_code(0x0000) - not-present page

PGD 0 P4D 0

Oops: 0000 [#1] PREEMPT SMP PTI

CPU: 1 PID: 50309 Comm: nginx Kdump: loaded Tainted: G E 5.16.0-rc4+ #53

RIP: 0010:smc_setsockopt+0x59/0x280 [smc]

Call Trace:

<TASK>

__sys_setsockopt+0xfc/0x190

__x64_sys_setsockopt+0x20/0x30

do_syscall_64+0x34/0x90

entry_SYSCALL_64_after_hwframe+0x44/0xae

RIP: 0033:0x7f16ba83918e

</TASK>

This patch tries to fix it by holding clcsock_release_lock and

checking whether clcsock has already been released before access.

In case that a crash of the same reason happens in smc_getsockopt()

or smc_switch_to_fallback(), this patch also checkes

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References