4.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Soheil Hassas Yeganeh <soheil@xxxxxxxxxx>
[ Upstream commit 8605330aac5a5785630aec8f64378a54891937cc ]
__sock_recv_timestamp can be called for both normal skbs (for
receive timestamps) and for skbs on the error queue (for transmit
timestamps).
Commit 1c885808e456
(tcp: SOF_TIMESTAMPING_OPT_STATS option for SO_TIMESTAMPING)
assumes any skb passed to __sock_recv_timestamp are from
the error queue, containing OPT_STATS in the content of the skb.
This results in accessing invalid memory or generating junk
data.
To fix this, set skb->pkt_type to PACKET_OUTGOING for packets
on the error queue. This is safe because on the receive path
on local sockets skb->pkt_type is never set to PACKET_OUTGOING.
With that, copy OPT_STATS from a packet, only if its pkt_type
is PACKET_OUTGOING.
Fixes: 1c885808e456 ("tcp: SOF_TIMESTAMPING_OPT_STATS option for SO_TIMESTAMPING")
Reported-by: JongHwan Kim <zzoru007@xxxxxxxxx>
Signed-off-by: Soheil Hassas Yeganeh <soheil@xxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Willem de Bruijn <willemb@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/core/skbuff.c | 10 ++++++++++
net/socket.c | 13 ++++++++++++-
2 files changed, 22 insertions(+), 1 deletion(-)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3700,6 +3700,15 @@ static void sock_rmem_free(struct sk_buf
atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
}
+static void skb_set_err_queue(struct sk_buff *skb)
+{
+ /* pkt_type of skbs received on local sockets is never PACKET_OUTGOING.
+ * So, it is safe to (mis)use it to mark skbs on the error queue.
+ */
+ skb->pkt_type = PACKET_OUTGOING;
+ BUILD_BUG_ON(PACKET_OUTGOING == 0);
+}
+
/*
* Note: We dont mem charge error packets (no sk_forward_alloc changes)
*/
@@ -3713,6 +3722,7 @@ int sock_queue_err_skb(struct sock *sk,
skb->sk = sk;
skb->destructor = sock_rmem_free;
atomic_add(skb->truesize, &sk->sk_rmem_alloc);
+ skb_set_err_queue(skb);
/* before exiting rcu section, make sure dst is refcounted */
skb_dst_force(skb);
--- a/net/socket.c
+++ b/net/socket.c
@@ -654,6 +654,16 @@ int kernel_sendmsg(struct socket *sock,
}
EXPORT_SYMBOL(kernel_sendmsg);
+static bool skb_is_err_queue(const struct sk_buff *skb)
+{
+ /* pkt_type of skbs enqueued on the error queue are set to
+ * PACKET_OUTGOING in skb_set_err_queue(). This is only safe to do
+ * in recvmsg, since skbs received on a local socket will never
+ * have a pkt_type of PACKET_OUTGOING.
+ */
+ return skb->pkt_type == PACKET_OUTGOING;
+}
+
/*
* called from sock_recv_timestamp() if sock_flag(sk, SOCK_RCVTSTAMP)
*/
@@ -697,7 +707,8 @@ void __sock_recv_timestamp(struct msghdr
put_cmsg(msg, SOL_SOCKET,
SCM_TIMESTAMPING, sizeof(tss), &tss);
- if (skb->len && (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_STATS))
+ if (skb_is_err_queue(skb) && skb->len &&
+ (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_STATS))
put_cmsg(msg, SOL_SOCKET, SCM_TIMESTAMPING_OPT_STATS,
skb->len, skb->data);
}