CVE-2026-46330: Revert "net/smc: Introduce TCP ULP support"

CVE-2026-46330: Revert "net/smc: Introduce TCP ULP support"

[Greg Kroah-Hartman]

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

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

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

Revert "net/smc: Introduce TCP ULP support"

This reverts commit d7cd421da9da2cc7b4d25b8537f66db5c8331c40.

As reported by Al Viro, the TCP ULP support for SMC is fundamentally
broken. The implementation attempts to convert an active TCP socket
into an SMC socket by modifying the underlying `struct file`, dentry,
and inode in-place, which violates core VFS invariants that assume
these structures are immutable for an open file, creating a risk of
use after free errors and general system instability.

Given the severity of this design flaw and the fact that cleaner
alternatives (e.g., LD_PRELOAD, BPF) exist for legacy application
transparency, the correct course of action is to remove this feature
entirely.

The Linux kernel CVE team has assigned CVE-2026-46330 to this issue.


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

	Issue introduced in 5.17 with commit d7cd421da9da2cc7b4d25b8537f66db5c8331c40 and fixed in 6.19.4 with commit 6c505d95c69e27dbf28fea29dc84d2498d69515c
	Issue introduced in 5.17 with commit d7cd421da9da2cc7b4d25b8537f66db5c8331c40 and fixed in 7.0 with commit df31a6b0a3057e66994ad6ccf5d95b9b9514f033

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-2026-46330
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/smc/af_smc.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/6c505d95c69e27dbf28fea29dc84d2498d69515c
	https://git.kernel.org/stable/c/df31a6b0a3057e66994ad6ccf5d95b9b9514f033