| Message ID | 1520366221-12350-1-git-send-email-alexey.kodanev@oracle.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net] dccp: check sk for closed state in dccp_sendmsg() | expand |
From: Alexey Kodanev <alexey.kodanev@oracle.com> Date: Tue, 6 Mar 2018 22:57:01 +0300 > dccp_disconnect() sets 'dp->dccps_hc_tx_ccid' tx handler to NULL, > therefore if DCCP socket is disconnected and dccp_sendmsg() is > called after it, it will cause a NULL pointer dereference in > dccp_write_xmit(). > > This crash and the reproducer was reported by syzbot. Looks like > it is reproduced if commit 69c64866ce07 ("dccp: CVE-2017-8824: > use-after-free in DCCP code") is applied. > > Reported-by: syzbot+f99ab3887ab65d70f816@syzkaller.appspotmail.com > Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com> Applied and queued up for -stable, thanks!
diff --git a/net/dccp/proto.c b/net/dccp/proto.c index 15bdc00..84cd4e3 100644 --- a/net/dccp/proto.c +++ b/net/dccp/proto.c @@ -794,6 +794,11 @@ int dccp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) if (skb == NULL) goto out_release; + if (sk->sk_state == DCCP_CLOSED) { + rc = -ENOTCONN; + goto out_discard; + } + skb_reserve(skb, sk->sk_prot->max_header); rc = memcpy_from_msg(skb_put(skb, len), msg, len); if (rc != 0)
dccp_disconnect() sets 'dp->dccps_hc_tx_ccid' tx handler to NULL, therefore if DCCP socket is disconnected and dccp_sendmsg() is called after it, it will cause a NULL pointer dereference in dccp_write_xmit(). This crash and the reproducer was reported by syzbot. Looks like it is reproduced if commit 69c64866ce07 ("dccp: CVE-2017-8824: use-after-free in DCCP code") is applied. Reported-by: syzbot+f99ab3887ab65d70f816@syzkaller.appspotmail.com Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com> --- net/dccp/proto.c | 5 +++++ 1 file changed, 5 insertions(+)