From: Eric Dumazet <[email protected]>
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 <[email protected]>
Reported-by: Pray3r <[email protected]>
Reported-by: Andrey Konovalov <[email protected]>
Tested-by: Andrey Konovalov <[email protected]>
---
Notes:
- day-0 bug.
- Not sure if it makes sense for TCP socket to be able to join MC
group ?
net/ipv4/tcp_minisocks.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index
717be4de53248352c758b50557987d898340dd4f..03035e2857fc8b6e4cd8af6e46e81048d4de9105
100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -448,6 +448,7 @@ struct sock *tcp_create_openreq_child(const struct sock *sk,
minmax_reset(&newtp->rtt_min, tcp_time_stamp, ~0U);
newicsk->icsk_rto = TCP_TIMEOUT_INIT;
newicsk->icsk_ack.lrcvtime = tcp_time_stamp;
+ newicsk->icsk_inet.mc_list = NULL;
newtp->packets_out = 0;
newtp->retrans_out = 0;
