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Commit 657831ff authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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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 8b485ce6 ("tcp: do not inherit
fastopen_req from parent")

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

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarPray3r <pray3r.z@gmail.com>
Reported-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Tested-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e735da5e

net/ipv4/inet_connection_sock.c

+2 −0
Original line number Diff line number Diff line
@@ -794,6 +794,8 @@ struct sock *inet_csk_clone_lock(const struct sock *sk, 
		/* listeners have SOCK_RCU_FREE, not the children */

		sock_reset_flag(newsk, SOCK_RCU_FREE);



		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));