Description (CNA)
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]).
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected df132eff463873e14e019a07f387b4d577d6d1f9 before 547762250220325d350d0917a7231480e0f4142b; affected df132eff463873e14e019a07f387b4d577d6d1f9 before 3257386be6a7eb8a8bfc9cbfb746df4eb4fc70e8; affected df132eff463873e14e019a07f387b4d577d6d1f9 before 0f7df4899299ce4662e5f95badb9dbc57cc37fa5; affected df132eff463873e14e019a07f387b4d577d6d1f9 before 7a63f4fb0efb4e69efd990cbb740a848679ec4b0; affected df132eff463873e14e019a07f387b4d577d6d1f9 before c6fefcb71d246baaf3bacdad1af7ff50ebcfe652; affected df132eff463873e14e019a07f387b4d577d6d1f9 before 9e7c37fadb3be1fc33073fcf10aa96d166caa697; affected df132eff463873e14e019a07f387b4d577d6d1f9 before 5bc83bdf5f5b8010d1ca5a4555537e62413ab4e2; affected df132eff463873e14e019a07f387b4d577d6d1f9 before 2e5068b7e0ae0a54f6cfd03a2f80977da657f1ee; affected df132eff463873e14e019a07f387b4d577d6d1f9 before f1a69a940de58b16e8249dff26f74c8cc59b32be; affected 26e51e5287eed4d96ea66a3da95429f42940f013; affected 8b97e045bd6d37f96f161e4d371ae174148e1587; affected e044554e97e812eb257d073bcc130e0ea653858f; affected 8376fdc999be008f0e9918db52f1ed8c08f5a1c9; affected cd947138e8c31e8cfcd489c12e9b97271beb6e79; affected 3.18.128 before 3.19; affected 4.4.166 before 4.5; affected 4.9.142 before 4.10; affected 4.14.85 before 4.15; affected 4.19.6 before 4.20 |
| Linux / Linux | affected 4.20; unaffected 0 before 4.20; unaffected 5.4.293 through 5.4.*; unaffected 5.10.237 through 5.10.*; unaffected 5.15.181 through 5.15.*; unaffected 6.1.135 through 6.1.*; unaffected 6.6.88 through 6.6.*; unaffected 6.12.24 through 6.12.*; unaffected 6.13.12 through 6.13.*; unaffected 6.14.3 through 6.14.*; unaffected 6.15 through * |
CWE
No CWE identifiers supplied.
References
- 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
ADP enrichment
No English description supplied.
No English description supplied.
No references supplied.