net: fix sk_forward_alloc corruptions

As David found out, sock_queue_err_skb() should be called with socket
lock hold, or we risk sk_forward_alloc corruption, since we use non
atomic operations to update this field.

This patch adds bh_lock_sock()/bh_unlock_sock() pair to three spots.
(BH already disabled)

1) skb_tstamp_tx()
2) Before calling ip_icmp_error(), in __udp4_lib_err()
3) Before calling ipv6_icmp_error(), in __udp6_lib_err()

Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 4667d4d..f2913ae 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2992,7 +2992,11 @@ void skb_tstamp_tx(struct sk_buff *orig_skb,
        memset(serr, 0, sizeof(*serr));
        serr->ee.ee_errno = ENOMSG;
        serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
        memset(serr, 0, sizeof(*serr));
        serr->ee.ee_errno = ENOMSG;
        serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;

+
+       bh_lock_sock(sk);

        err = sock_queue_err_skb(sk, skb);
        err = sock_queue_err_skb(sk, skb);

+       bh_unlock_sock(sk);
+

        if (err)
                kfree_skb(skb);
 }
        if (err)
                kfree_skb(skb);
 }

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index b9d0d40..acdc9be 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -634,7 +634,9 @@ void __udp4_lib_err(struct sk_buff *skb, u32 info, struct udp_table *udptable)
                if (!harderr || sk->sk_state != TCP_ESTABLISHED)
                        goto out;
        } else {
                if (!harderr || sk->sk_state != TCP_ESTABLISHED)
                        goto out;
        } else {

+               bh_lock_sock(sk);

                ip_icmp_error(sk, skb, err, uh->dest, info, (u8 *)(uh+1));
                ip_icmp_error(sk, skb, err, uh->dest, info, (u8 *)(uh+1));

+               bh_unlock_sock(sk);

        }
        sk->sk_err = err;
        sk->sk_error_report(sk);
        }
        sk->sk_err = err;
        sk->sk_error_report(sk);

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 87be586..3048f90 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -466,9 +466,11 @@ void __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
        if (sk->sk_state != TCP_ESTABLISHED && !np->recverr)
                goto out;
 
        if (sk->sk_state != TCP_ESTABLISHED && !np->recverr)
                goto out;
 

-       if (np->recverr)
+       if (np->recverr) {
+               bh_lock_sock(sk);

                ipv6_icmp_error(sk, skb, err, uh->dest, ntohl(info), (u8 *)(uh+1));
                ipv6_icmp_error(sk, skb, err, uh->dest, ntohl(info), (u8 *)(uh+1));

-
+               bh_unlock_sock(sk);
+       }

        sk->sk_err = err;
        sk->sk_error_report(sk);
 out:
        sk->sk_err = err;
        sk->sk_error_report(sk);
 out: