On Sat, Mar 16, 2019 at 10:09 PM syzbot
[off-list ref] wrote:

syzbot has bisected this bug to:

commit 89664c623617b1d34447a927ac7871ddf3db29d3
Author: Xin Long [off-list ref]
Date:   Sun Mar 3 09:54:53 2019 +0000

     sctp: sctp_sock_migrate() returns error if sctp_bind_addr_dup() fails

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=17b17777200000
start commit:   89664c62 sctp: sctp_sock_migrate() returns error if sctp_b..
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=14717777200000
console output: https://syzkaller.appspot.com/x/log.txt?x=10717777200000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b613f0327d980b6b
dashboard link: https://syzkaller.appspot.com/bug?extid=85e0b422ff140b03672a
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12613b13200000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10f1884d200000

Reported-by: syzbot+85e0b422ff140b03672a@syzkaller.appspotmail.com
Fixes: 89664c62 ("sctp: sctp_sock_migrate() returns error if
sctp_bind_addr_dup() fails")

sctp_copy_descendant() coplied sctp_sock->pd_lobby. we should fix it with:

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 06c6f4a..e0857dd 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c

@@ -9175,7 +9175,7 @@ static inline void sctp_copy_descendant(struct

sock *sk_to,
 {
  int ancestor_size = sizeof(struct inet_sock) +
      sizeof(struct sctp_sock) -
-     offsetof(struct sctp_sock, auto_asconf_list);
+     offsetof(struct sctp_sock, pd_lobby);

  if (sk_from->sk_family == PF_INET6)
  ancestor_size += sizeof(struct ipv6_pinfo);