From 7c8387cf87181a6b8ef5d0178e1df6ea9132f915 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 9 May 2017 06:29:19 -0700 Subject: [PATCH] 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 ! Signed-off-by: Eric Dumazet Reported-by: Pray3r Reported-by: Andrey Konovalov Tested-by: Andrey Konovalov Signed-off-by: David S. Miller Gbp-Pq: Topic bugfix/all Gbp-Pq: Name dccp-tcp-do-not-inherit-mc_list-from-parent.patch --- 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 61a9deec299..cf3d5674846 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -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)); -- 2.30.2