linux-cve-announce - CVE-2025-37756: net: tls: explicitly disallow disconnect

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Message-ID: <2025050139-CVE-2025-37756-a06e@gregkh>
Date: Thu,  1 May 2025 14:57:02 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-37756: net: tls: explicitly disallow disconnect

From: Greg Kroah-Hartman <gregkh@...nel.org>

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

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

net: tls: explicitly disallow disconnect

syzbot discovered that it can disconnect a TLS socket and then
run into all sort of unexpected corner cases. I have a vague
recollection of Eric pointing this out to us a long time ago.
Supporting disconnect is really hard, for one thing if offload
is enabled we'd need to wait for all packets to be _acked_.
Disconnect is not commonly used, disallow it.

The immediate problem syzbot run into is the warning in the strp,
but that's just the easiest bug to trigger:

  WARNING: CPU: 0 PID: 5834 at net/tls/tls_strp.c:486 tls_strp_msg_load+0x72e/0xa80 net/tls/tls_strp.c:486
  RIP: 0010:tls_strp_msg_load+0x72e/0xa80 net/tls/tls_strp.c:486
  Call Trace:
   <TASK>
   tls_rx_rec_wait+0x280/0xa60 net/tls/tls_sw.c:1363
   tls_sw_recvmsg+0x85c/0x1c30 net/tls/tls_sw.c:2043
   inet6_recvmsg+0x2c9/0x730 net/ipv6/af_inet6.c:678
   sock_recvmsg_nosec net/socket.c:1023 [inline]
   sock_recvmsg+0x109/0x280 net/socket.c:1045
   __sys_recvfrom+0x202/0x380 net/socket.c:2237

The Linux kernel CVE team has assigned CVE-2025-37756 to this issue.


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

	Issue introduced in 4.13 with commit 3c4d7559159bfe1e3b94df3a657b2cda3a34e218 and fixed in 6.1.135 with commit f3ce4d3f874ab7919edca364c147ac735f9f1d04
	Issue introduced in 4.13 with commit 3c4d7559159bfe1e3b94df3a657b2cda3a34e218 and fixed in 6.6.88 with commit 2bcad8fefcecdd5f005d8c550b25d703c063c34a
	Issue introduced in 4.13 with commit 3c4d7559159bfe1e3b94df3a657b2cda3a34e218 and fixed in 6.12.24 with commit 9fcbca0f801580cbb583e9cb274e2c7fbe766ca6
	Issue introduced in 4.13 with commit 3c4d7559159bfe1e3b94df3a657b2cda3a34e218 and fixed in 6.13.12 with commit c665bef891e8972e1d3ce5bbc0d42a373346a2c3
	Issue introduced in 4.13 with commit 3c4d7559159bfe1e3b94df3a657b2cda3a34e218 and fixed in 6.14.3 with commit 8513411ec321942bd3cfed53d5bb700665c67d86
	Issue introduced in 4.13 with commit 3c4d7559159bfe1e3b94df3a657b2cda3a34e218 and fixed in 6.15-rc2 with commit 5071a1e606b30c0c11278d3c6620cd6a24724cf6

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-2025-37756
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/tls/tls_main.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/f3ce4d3f874ab7919edca364c147ac735f9f1d04
	https://git.kernel.org/stable/c/2bcad8fefcecdd5f005d8c550b25d703c063c34a
	https://git.kernel.org/stable/c/9fcbca0f801580cbb583e9cb274e2c7fbe766ca6
	https://git.kernel.org/stable/c/c665bef891e8972e1d3ce5bbc0d42a373346a2c3
	https://git.kernel.org/stable/c/8513411ec321942bd3cfed53d5bb700665c67d86
	https://git.kernel.org/stable/c/5071a1e606b30c0c11278d3c6620cd6a24724cf6