Commit 7307bbc5 authored May 09, 2017 by Eric Dumazet Committed by Usaamah Patel Feb 12, 2018

dccp/tcp: do not inherit mc_list from parent



syzkaller found a way to trigger double frees from ip_mc_drop_socket()

It turns out that leave a copy of parent mc_list at accept() time,
which is very bad.

Very similar to commit 8b485ce69876 ("tcp: do not inherit
fastopen_req from parent")

Initial report from Pray3r, completed by Andrey one.
Thanks a lot to them !

Change-Id: I431b90eae7874a2ba726677b295ecce09e1a8fd1
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Pray3r <pray3r.z@gmail.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent c1308685

net/ipv4/inet_connection_sock.c

+2 −0

Original line number	Original line	Diff line number	Diff line
	@@ -706,6 +706,8 @@ struct sock inet_csk_clone_lock(const struct sock sk,
	inet_sk(newsk)->inet_sport = inet_rsk(req)->loc_port;		inet_sk(newsk)->inet_sport = inet_rsk(req)->loc_port;
	newsk->sk_write_space = sk_stream_write_space;		newsk->sk_write_space = sk_stream_write_space;

			inet_sk(newsk)->mc_list = NULL;

	newsk->sk_mark = inet_rsk(req)->ir_mark;		newsk->sk_mark = inet_rsk(req)->ir_mark;

	newicsk->icsk_retransmits = 0;		newicsk->icsk_retransmits = 0;