mirror of
https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10.git
synced 2026-09-09 00:07:04 +08:00
CKI KWF Bot
3a4c716a67
MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10/-/merge_requests/2479
JIRA: https://redhat.atlassian.net/browse/RHEL-171511
CVE: CVE-2026-31669
```
commit 9b55b253907e7431210483519c5ad711a37dafa1
Author: Jiayuan Chen <jiayuan.chen@linux.dev>
Date: Mon Apr 6 11:15:10 2026 +0800
mptcp: fix slab-use-after-free in __inet_lookup_established
The ehash table lookups are lockless and rely on
SLAB_TYPESAFE_BY_RCU to guarantee socket memory stability
during RCU read-side critical sections. Both tcp_prot and
tcpv6_prot have their slab caches created with this flag
via proto_register().
However, MPTCP's mptcp_subflow_init() copies tcpv6_prot into
tcpv6_prot_override during inet_init() (fs_initcall, level 5),
before inet6_init() (module_init/device_initcall, level 6) has
called proto_register(&tcpv6_prot). At that point,
tcpv6_prot.slab is still NULL, so tcpv6_prot_override.slab
remains NULL permanently.
This causes MPTCP v6 subflow child sockets to be allocated via
kmalloc (falling into kmalloc-4k) instead of the TCPv6 slab
cache. The kmalloc-4k cache lacks SLAB_TYPESAFE_BY_RCU, so
when these sockets are freed without SOCK_RCU_FREE (which is
cleared for child sockets by design), the memory can be
immediately reused. Concurrent ehash lookups under
rcu_read_lock can then access freed memory, triggering a
slab-use-after-free in __inet_lookup_established.
Fix this by splitting the IPv6-specific initialization out of
mptcp_subflow_init() into a new mptcp_subflow_v6_init(), called
from mptcp_proto_v6_init() before protocol registration. This
ensures tcpv6_prot_override.slab correctly inherits the
SLAB_TYPESAFE_BY_RCU slab cache.
Fixes: b19bc2945b ("mptcp: implement delegated actions")
Cc: stable@vger.kernel.org
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260406031512.189159-1-jiayuan.chen@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
```
Signed-off-by: CKI Backport Bot <cki-ci-bot+cki-gitlab-backport-bot@redhat.com>
[^footer]: Created 2026-04-28 12:12 UTC by backporter - [KWF FAQ](https://red.ht/kernel_workflow_doc) - [Slack #team-kernel-workflow](https://redhat-internal.slack.com/archives/C04LRUPMJQ5) - [Source](https://gitlab.com/cki-project/kernel-workflow/-/blob/main/webhook/utils/backporter.py) - [Documentation](https://gitlab.com/cki-project/kernel-workflow/-/blob/main/docs/README.backporter.md) - [Report an issue](https://redhat.atlassian.net/secure/CreateIssueDetails!init.jspa?pid=12334433&issuetype=1&priority=4&summary=backporter+webhook+issue&components=kernel-workflow+/+backporter) [^footer]
Approved-by: Paolo Abeni <pabeni@redhat.com>
Approved-by: Davide Caratti <dcaratti@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>
Merged-by: CKI GitLab Kmaint Pipeline Bot <26919896-cki-kmaint-pipeline-bot@users.noreply.gitlab.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.