From: Eric Dumazet Date: Tue, 9 May 2017 13:29:19 +0000 (-0700) Subject: dccp/tcp: do not inherit mc_list from parent X-Git-Tag: archive/raspbian/4.9.51-1+rpi1~8^2^2^2~55 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=3dc17477d80682c25bf2a30cdb83759fc8f3f28a;p=linux-4.9.git 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 --- diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 61a9deec2993..cf3d5674846a 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));