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: v4.12-rc1~47^2 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=657831ffc38e30092a2d5f03d385d710eb88b09a;p=platform%2Fkernel%2Flinux-exynos.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 --- diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 5e313c1..1054d33 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -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));