* [PATCH net] dccp: check sk for closed state in dccp_sendmsg()
@ 2018-03-06 19:57 Alexey Kodanev
2018-03-07 18:39 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Alexey Kodanev @ 2018-03-06 19:57 UTC (permalink / raw)
To: netdev; +Cc: Eric Dumazet, David Miller, Alexey Kodanev
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(+)
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)
--
1.8.3.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net] dccp: check sk for closed state in dccp_sendmsg()
2018-03-06 19:57 [PATCH net] dccp: check sk for closed state in dccp_sendmsg() Alexey Kodanev
@ 2018-03-07 18:39 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2018-03-07 18:39 UTC (permalink / raw)
To: alexey.kodanev; +Cc: netdev, edumazet
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!
^ permalink raw reply [flat|nested] 2+ messages in thread
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2018-03-06 19:57 [PATCH net] dccp: check sk for closed state in dccp_sendmsg() Alexey Kodanev
2018-03-07 18:39 ` David Miller
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