CVE-2017-15115: Linux kernel: sctp: use-after-free in sctp_cmp_addr_exact()

[Vladis Dronov <vdronov () redhat com>]

Heololo,

It was found that in Linux kernel when peeling off an association to the socket
in another network namespace, all transports in this association are not to be
rehashed and keep use the old key in hashtable. A kernel would miss removing
transports from hashtable when closing the socket and all transports are being
freed. Later on a use-after-free could be caused when looking up an association
and dereferencing the transports.

This is a very old issue and it was fixed in Linux kernel v4.14-rc6, and may still
be not fixed in other distributions.

References:

https://bugzilla.redhat.com/show_bug.cgi?id=1513345

https://patchwork.ozlabs.org/patch/827077/

An upstream patch:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=df80cd9b28b9ebaa284a41df611dbf3a2d05ca74

PS: I do not see that this fix has got into any stable tree, so posting about this
bug instead of the 100 other bugfixes in the past few weeks/months.

Best regards,
Vladis Dronov | Red Hat, Inc. | Product Security Engineer