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dccp/tcp: do not inherit mc_list from parent

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[ 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>
This commit is contained in:
Eric Dumazet 2017-05-09 06:29:19 -07:00 committed by Greg Kroah-Hartman
parent db3fd4527e
commit 4eed440295
1 changed files with 2 additions and 0 deletions
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2
net/ipv4/inet_connection_sock.c
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@ -665,6 +665,8 @@ 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));