Commit 5f67a166 authored May 09, 2017 by Eric Dumazet Committed by Greg Kroah-Hartman Jun 07, 2017

dccp/tcp: do not inherit mc_list from parent




[ Upstream commit 657831ffc38e30092a2d5f03d385d710eb88b09a ]

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 !

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent b9978c27

net/ipv4/inet_connection_sock.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -669,6 +669,8 @@ struct sock inet_csk_clone_lock(const struct sock sk,
		inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
		newsk->sk_write_space = sk_stream_write_space;

		inet_sk(newsk)->mc_list = NULL;

		newsk->sk_mark = inet_rsk(req)->ir_mark;
		atomic64_set(&newsk->sk_cookie,
		atomic64_read(&inet_rsk(req)->ir_cookie));