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: v3.10.106~3 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2f954a6249770ef5f2588aab0ca182238028628f;p=thirdparty%2Fkernel%2Fstable.git dccp/tcp: do not inherit mc_list from parent commit 657831ffc38e30092a2d5f03d385d710eb88b09a upstream. 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 Signed-off-by: Willy Tarreau --- diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 6acb541c90910..40ac1e2cbb34c 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -688,6 +688,8 @@ struct sock *inet_csk_clone_lock(const struct sock *sk, inet_sk(newsk)->inet_sport = inet_rsk(req)->loc_port; newsk->sk_write_space = sk_stream_write_space; + inet_sk(newsk)->mc_list = NULL; + newicsk->icsk_retransmits = 0; newicsk->icsk_backoff = 0; newicsk->icsk_probes_out = 0;