From fa0ad0349d68f7e86419922266aa48de3eb2c507 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 6 Jun 2017 18:16:00 +0200 Subject: [PATCH] dccp/tcp: do not inherit mc_list from parent MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reported-by: Pray3r Reported-by: Andrey Konovalov Tested-by: Andrey Konovalov Signed-off-by: David S. Miller CVE-2017-8890 (cherry-picked from 657831ffc38e30092a2d5f03d385d710eb88b09a) Signed-off-by: Stefan Bader Acked-by: Colin Ian King Acked-by: Andy Whitcroft Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Fabian Grünbichler --- net/ipv4/inet_connection_sock.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 19ea045c50ed..d952cfa15737 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -669,6 +669,8 @@ 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)); -- 2.11.0