dccp: check sk for closed state in dccp_sendmsg()
authorAlexey Kodanev <alexey.kodanev@oracle.com>
Tue, 6 Mar 2018 19:57:01 +0000 (22:57 +0300)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 31 Mar 2018 16:10:40 +0000 (18:10 +0200)
commit91d27e0c302501e148460db9981b5b04481781ce
treef6aef06284ebe9beed73838bcbfeb4ef090cdd33
parent946b9671ac02842c454f4da7b560feb9c84a4356
dccp: check sk for closed state in dccp_sendmsg()

[ Upstream commit 67f93df79aeefc3add4e4b31a752600f834236e2 ]

dccp_disconnect() sets 'dp->dccps_hc_tx_ccid' tx handler to NULL,
therefore if DCCP socket is disconnected and dccp_sendmsg() is
called after it, it will cause a NULL pointer dereference in
dccp_write_xmit().

This crash and the reproducer was reported by syzbot. Looks like
it is reproduced if commit 69c64866ce07 ("dccp: CVE-2017-8824:
use-after-free in DCCP code") is applied.

Reported-by: syzbot+f99ab3887ab65d70f816@syzkaller.appspotmail.com
Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net/dccp/proto.c