CVE-2025-21670

/// Technical description

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

vsock/bpf: return early if transport is not assigned

Some of the core functions can only be called if the transport

has been assigned.

As Michal reported, a socket might have the transport at NULL,

for example after a failed connect(), causing the following trace:

BUG: kernel NULL pointer dereference, address: 00000000000000a0

#PF: supervisor read access in kernel mode

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

PGD 12faf8067 P4D 12faf8067 PUD 113670067 PMD 0

Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI

CPU: 15 UID: 0 PID: 1198 Comm: a.out Not tainted 6.13.0-rc2+

RIP: 0010:vsock_connectible_has_data+0x1f/0x40

Call Trace:

vsock_bpf_recvmsg+0xca/0x5e0

sock_recvmsg+0xb9/0xc0

__sys_recvfrom+0xb3/0x130

__x64_sys_recvfrom+0x20/0x30

do_syscall_64+0x93/0x180

entry_SYSCALL_64_after_hwframe+0x76/0x7e

So we need to check the `vsk->transport` in vsock_bpf_recvmsg(),

espe

/// 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