| From bippy-1.2.0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@kernel.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2025-23142: sctp: detect and prevent references to a freed transport in sendmsg |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| sctp: detect and prevent references to a freed transport in sendmsg |
| |
| sctp_sendmsg() re-uses associations and transports when possible by |
| doing a lookup based on the socket endpoint and the message destination |
| address, and then sctp_sendmsg_to_asoc() sets the selected transport in |
| all the message chunks to be sent. |
| |
| There's a possible race condition if another thread triggers the removal |
| of that selected transport, for instance, by explicitly unbinding an |
| address with setsockopt(SCTP_SOCKOPT_BINDX_REM), after the chunks have |
| been set up and before the message is sent. This can happen if the send |
| buffer is full, during the period when the sender thread temporarily |
| releases the socket lock in sctp_wait_for_sndbuf(). |
| |
| This causes the access to the transport data in |
| sctp_outq_select_transport(), when the association outqueue is flushed, |
| to result in a use-after-free read. |
| |
| This change avoids this scenario by having sctp_transport_free() signal |
| the freeing of the transport, tagging it as "dead". In order to do this, |
| the patch restores the "dead" bit in struct sctp_transport, which was |
| removed in |
| commit 47faa1e4c50e ("sctp: remove the dead field of sctp_transport"). |
| |
| Then, in the scenario where the sender thread has released the socket |
| lock in sctp_wait_for_sndbuf(), the bit is checked again after |
| re-acquiring the socket lock to detect the deletion. This is done while |
| holding a reference to the transport to prevent it from being freed in |
| the process. |
| |
| If the transport was deleted while the socket lock was relinquished, |
| sctp_sendmsg_to_asoc() will return -EAGAIN to let userspace retry the |
| send. |
| |
| The bug was found by a private syzbot instance (see the error report [1] |
| and the C reproducer that triggers it [2]). |
| |
| The Linux kernel CVE team has assigned CVE-2025-23142 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 4.20 with commit df132eff463873e14e019a07f387b4d577d6d1f9 and fixed in 5.4.293 with commit 547762250220325d350d0917a7231480e0f4142b |
| Issue introduced in 4.20 with commit df132eff463873e14e019a07f387b4d577d6d1f9 and fixed in 5.10.237 with commit 3257386be6a7eb8a8bfc9cbfb746df4eb4fc70e8 |
| Issue introduced in 4.20 with commit df132eff463873e14e019a07f387b4d577d6d1f9 and fixed in 5.15.181 with commit 0f7df4899299ce4662e5f95badb9dbc57cc37fa5 |
| Issue introduced in 4.20 with commit df132eff463873e14e019a07f387b4d577d6d1f9 and fixed in 6.1.135 with commit 7a63f4fb0efb4e69efd990cbb740a848679ec4b0 |
| Issue introduced in 4.20 with commit df132eff463873e14e019a07f387b4d577d6d1f9 and fixed in 6.6.88 with commit c6fefcb71d246baaf3bacdad1af7ff50ebcfe652 |
| Issue introduced in 4.20 with commit df132eff463873e14e019a07f387b4d577d6d1f9 and fixed in 6.12.24 with commit 9e7c37fadb3be1fc33073fcf10aa96d166caa697 |
| Issue introduced in 4.20 with commit df132eff463873e14e019a07f387b4d577d6d1f9 and fixed in 6.13.12 with commit 5bc83bdf5f5b8010d1ca5a4555537e62413ab4e2 |
| Issue introduced in 4.20 with commit df132eff463873e14e019a07f387b4d577d6d1f9 and fixed in 6.14.3 with commit 2e5068b7e0ae0a54f6cfd03a2f80977da657f1ee |
| Issue introduced in 4.20 with commit df132eff463873e14e019a07f387b4d577d6d1f9 and fixed in 6.15 with commit f1a69a940de58b16e8249dff26f74c8cc59b32be |
| Issue introduced in 3.18.128 with commit 26e51e5287eed4d96ea66a3da95429f42940f013 |
| Issue introduced in 4.4.166 with commit 8b97e045bd6d37f96f161e4d371ae174148e1587 |
| Issue introduced in 4.9.142 with commit e044554e97e812eb257d073bcc130e0ea653858f |
| Issue introduced in 4.14.85 with commit 8376fdc999be008f0e9918db52f1ed8c08f5a1c9 |
| Issue introduced in 4.19.6 with commit cd947138e8c31e8cfcd489c12e9b97271beb6e79 |
| |
| 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-2025-23142 |
| 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: |
| include/net/sctp/structs.h |
| net/sctp/socket.c |
| net/sctp/transport.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/547762250220325d350d0917a7231480e0f4142b |
| https://git.kernel.org/stable/c/3257386be6a7eb8a8bfc9cbfb746df4eb4fc70e8 |
| https://git.kernel.org/stable/c/0f7df4899299ce4662e5f95badb9dbc57cc37fa5 |
| https://git.kernel.org/stable/c/7a63f4fb0efb4e69efd990cbb740a848679ec4b0 |
| https://git.kernel.org/stable/c/c6fefcb71d246baaf3bacdad1af7ff50ebcfe652 |
| https://git.kernel.org/stable/c/9e7c37fadb3be1fc33073fcf10aa96d166caa697 |
| https://git.kernel.org/stable/c/5bc83bdf5f5b8010d1ca5a4555537e62413ab4e2 |
| https://git.kernel.org/stable/c/2e5068b7e0ae0a54f6cfd03a2f80977da657f1ee |
| https://git.kernel.org/stable/c/f1a69a940de58b16e8249dff26f74c8cc59b32be |
