From: Neil Horman <nhorman@tuxdriver.com>
Date: Mon, 12 Mar 2018 14:15:25 -0400
syzbot/kasan detected a double free in sctp_sendmsg_to_asoc:
BUG: KASAN: use-after-free in sctp_association_free+0x7b7/0x930
net/sctp/associola.c:332
Read of size 8 at addr ffff8801d8006ae0 by task syzkaller914861/4202
...
This was introduced by commit:
f84af33 sctp: factor out sctp_sendmsg_to_asoc from sctp_sendmsg
As the newly refactored function moved the wait_for_sndbuf call to a
point after the association was connected, allowing for peeloff events
to occur, which in turn caused wait_for_sndbuf to return -EPIPE which
was not caught by the logic that determines if an association should be
freed or not.
Fix it the easy way by returning the ordering of
sctp_primitive_ASSOCIATE and sctp_wait_for_sndbuf to the old order, to
ensure that EPIPE will not happen.
Tested by myself using the syzbot reproducers with positive results
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: davem@davemloft.net
CC: Xin Long <lucien.xin@gmail.com>
Reported-by: <redacted>
Applied, thanks Neil.