sctp: use init_tag from inithdr for ABORT chunk

[ Upstream commit 4f7019c7eb33967eb87766e0e4602b5576873680 ]

Currently Linux SCTP uses the verification tag of the existing SCTP
asoc when failing to process and sending the packet with the ABORT
chunk. This will result in the peer accepting the ABORT chunk and
removing the SCTP asoc. One could exploit this to terminate a SCTP
asoc.

This patch is to fix it by always using the initiate tag of the
received INIT chunk for the ABORT chunk to be sent.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>