CVE-2017-7558: Linux kernel: sctp: out-of-bounds read in inet_diag_msg_sctp{,l}addr_fill() and sctp_get_sctp_info()

[Vladis Dronov <vdronov () redhat com>]

Heololo,

A kernel data leak due to an out-of-bound read was found in Linux kernel in
inet_diag_msg_sctp{,l}addr_fill() and sctp_get_sctp_info() functions present
since v4.7-rc1 upto v4.13-rc6 including. A data leak happens when these functions
fill in sockaddr data structures used to export socket's diagnostic information.
As a result up to 100 bytes of the slab data could be leaked to a userspace.

Details: it is leaking exactly 100 bytes of a kernel slab whenever we answer to
a netlink request of type INET_DIAG_LOCALS or INET_DIAG_PEERS for a SCTP socket
(e.g. sent by the 'ss' tool included in the 'iproute2' package with 'ss -Si' or
'ss -Sm').

A researcher of this flaw and a patch author is Stefano Brivio of the Red Hat.

References:

https://bugzilla.redhat.com/show_bug.cgi?id=1480266

https://marc.info/?t=150348787500002&r=1&w=2

Suggested patch:

https://marc.info/?l=linux-netdev&m=150348777122761&w=2

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