cve/published/2025/CVE-2025-21854.mbox

From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: <linux-cve-announce@vger.kernel.org>
Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org>
Subject: CVE-2025-21854: sockmap, vsock: For connectible sockets allow only connected

Description
===========

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

sockmap, vsock: For connectible sockets allow only connected

sockmap expects all vsocks to have a transport assigned, which is expressed
in vsock_proto::psock_update_sk_prot(). However, there is an edge case
where an unconnected (connectible) socket may lose its previously assigned
transport. This is handled with a NULL check in the vsock/BPF recv path.

Another design detail is that listening vsocks are not supposed to have any
transport assigned at all. Which implies they are not supported by the
sockmap. But this is complicated by the fact that a socket, before
switching to TCP_LISTEN, may have had some transport assigned during a
failed connect() attempt. Hence, we may end up with a listening vsock in a
sockmap, which blows up quickly:

KASAN: null-ptr-deref in range [0x0000000000000120-0x0000000000000127]
CPU: 7 UID: 0 PID: 56 Comm: kworker/7:0 Not tainted 6.14.0-rc1+
Workqueue: vsock-loopback vsock_loopback_work
RIP: 0010:vsock_read_skb+0x4b/0x90
Call Trace:
 sk_psock_verdict_data_ready+0xa4/0x2e0
 virtio_transport_recv_pkt+0x1ca8/0x2acc
 vsock_loopback_work+0x27d/0x3f0
 process_one_work+0x846/0x1420
 worker_thread+0x5b3/0xf80
 kthread+0x35a/0x700
 ret_from_fork+0x2d/0x70
 ret_from_fork_asm+0x1a/0x30

For connectible sockets, instead of relying solely on the state of
vsk->transport, tell sockmap to only allow those representing established
connections. This aligns with the behaviour for AF_INET and AF_UNIX.

The Linux kernel CVE team has assigned CVE-2025-21854 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.4 with commit 634f1a7110b439c65fd8a809171c1d2d28bcea6f and fixed in 6.6.80 with commit cc9a7832ede53ade1ba9991f0e27314caa4029d8
	Issue introduced in 6.4 with commit 634f1a7110b439c65fd8a809171c1d2d28bcea6f and fixed in 6.12.17 with commit 22b683217ad2112791a708693cb236507abd637a
	Issue introduced in 6.4 with commit 634f1a7110b439c65fd8a809171c1d2d28bcea6f and fixed in 6.13.5 with commit f7b473e35986835cc2813fef7b9d40336a09247e
	Issue introduced in 6.4 with commit 634f1a7110b439c65fd8a809171c1d2d28bcea6f and fixed in 6.14 with commit 8fb5bb169d17cdd12c2dcc2e96830ed487d77a0f

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-21854
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	net/core/sock_map.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/cc9a7832ede53ade1ba9991f0e27314caa4029d8
	https://git.kernel.org/stable/c/22b683217ad2112791a708693cb236507abd637a
	https://git.kernel.org/stable/c/f7b473e35986835cc2813fef7b9d40336a09247e
	https://git.kernel.org/stable/c/8fb5bb169d17cdd12c2dcc2e96830ed487d77a0f