sctp: Fix sk_ack_backlog wrap-around problem
authorXufeng Zhang <xufeng.zhang@windriver.com>
Thu, 12 Jun 2014 02:53:36 +0000 (10:53 +0800)
committerJiri Slaby <jslaby@suse.cz>
Mon, 23 Jun 2014 08:28:04 +0000 (10:28 +0200)
commitddb638e68690ca61959775b262a5ef0719c5c066
treed40c279f0c60a18d9d6509e16f001da24d07915a
parentc671113b05eb8cdcc5ed8610e9cc45a653ea7558
sctp: Fix sk_ack_backlog wrap-around problem

[ Upstream commit d3217b15a19a4779c39b212358a5c71d725822ee ]

Consider the scenario:
For a TCP-style socket, while processing the COOKIE_ECHO chunk in
sctp_sf_do_5_1D_ce(), after it has passed a series of sanity check,
a new association would be created in sctp_unpack_cookie(), but afterwards,
some processing maybe failed, and sctp_association_free() will be called to
free the previously allocated association, in sctp_association_free(),
sk_ack_backlog value is decremented for this socket, since the initial
value for sk_ack_backlog is 0, after the decrement, it will be 65535,
a wrap-around problem happens, and if we want to establish new associations
afterward in the same socket, ABORT would be triggered since sctp deem the
accept queue as full.
Fix this issue by only decrementing sk_ack_backlog for associations in
the endpoint's list.

Fix-suggested-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Xufeng Zhang <xufeng.zhang@windriver.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
net/sctp/associola.c