net: fix sk_forward_alloc corruption

On UDP sockets, we must call skb_free_datagram() with socket locked,
or risk sk_forward_alloc corruption. This requirement is not respected
in SUNRPC.

Add a convenient helper, skb_free_datagram_locked() and use it in SUNRPC

Reported-by: Francis Moreau <francis.moro@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 6aebfceca3ebd348bd102c7775fb87a59ec54608..bcdd6606f46876c16a9dd64ab41639b77c12740e 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1757,6 +1757,8 @@ extern int               skb_copy_datagram_const_iovec(const struct sk_buff *from,
                                                     int to_offset,
                                                     int size);
 extern void           skb_free_datagram(struct sock *sk, struct sk_buff *skb);
+extern void           skb_free_datagram_locked(struct sock *sk,
+                                               struct sk_buff *skb);
 extern int            skb_kill_datagram(struct sock *sk, struct sk_buff *skb,
                                         unsigned int flags);
 extern __wsum         skb_checksum(const struct sk_buff *skb, int offset,

diff --git a/net/core/datagram.c b/net/core/datagram.c
index 1c6cf3a1a4f6abc3c605e492c4381d40103d3094..4ade3011bb3c2bd4d270cfb10cdcf5e112402ce9 100644 (file)
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -224,6 +224,15 @@ void skb_free_datagram(struct sock *sk, struct sk_buff *skb)
        consume_skb(skb);
        sk_mem_reclaim_partial(sk);
 }
+EXPORT_SYMBOL(skb_free_datagram);
+
+void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb)
+{
+       lock_sock(sk);
+       skb_free_datagram(sk, skb);
+       release_sock(sk);
+}
+EXPORT_SYMBOL(skb_free_datagram_locked);
 
 /**
  *     skb_kill_datagram - Free a datagram skbuff forcibly
@@ -752,5 +761,4 @@ unsigned int datagram_poll(struct file *file, struct socket *sock,
 EXPORT_SYMBOL(datagram_poll);
 EXPORT_SYMBOL(skb_copy_and_csum_datagram_iovec);
 EXPORT_SYMBOL(skb_copy_datagram_iovec);
-EXPORT_SYMBOL(skb_free_datagram);
 EXPORT_SYMBOL(skb_recv_datagram);

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index d0d436d6216c910eafb36742f3f50e85bac7e8a7..0fa9f70e4b1996f6af891f2984c1344675d62e2d 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -999,9 +999,7 @@ try_again:
                err = ulen;
 
 out_free:
-       lock_sock(sk);
-       skb_free_datagram(sk, skb);
-       release_sock(sk);
+       skb_free_datagram_locked(sk, skb);
 out:
        return err;
 

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 3a60f12b34ed053da8cf4261952d6d35ff879f28..cf538ed5ef6aadf849d42cdc4e046f00a0f8f51a 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -288,9 +288,7 @@ try_again:
                err = ulen;
 
 out_free:
-       lock_sock(sk);
-       skb_free_datagram(sk, skb);
-       release_sock(sk);
+       skb_free_datagram_locked(sk, skb);
 out:
        return err;
 

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index ccc5e83cae5d25cf592237025167d6d1b9d9c7bd..1c246a4f491e9ee5126a8bace259b32a91955421 100644 (file)
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -111,7 +111,7 @@ static void svc_release_skb(struct svc_rqst *rqstp)
                rqstp->rq_xprt_ctxt = NULL;
 
                dprintk("svc: service %p, releasing skb %p\n", rqstp, skb);
-               skb_free_datagram(svsk->sk_sk, skb);
+               skb_free_datagram_locked(svsk->sk_sk, skb);
        }
 }
 
@@ -578,7 +578,7 @@ static int svc_udp_recvfrom(struct svc_rqst *rqstp)
                                "svc: received unknown control message %d/%d; "
                                "dropping RPC reply datagram\n",
                                        cmh->cmsg_level, cmh->cmsg_type);
-               skb_free_datagram(svsk->sk_sk, skb);
+               skb_free_datagram_locked(svsk->sk_sk, skb);
                return 0;
        }
 
@@ -588,18 +588,18 @@ static int svc_udp_recvfrom(struct svc_rqst *rqstp)
                if (csum_partial_copy_to_xdr(&rqstp->rq_arg, skb)) {
                        local_bh_enable();
                        /* checksum error */
-                       skb_free_datagram(svsk->sk_sk, skb);
+                       skb_free_datagram_locked(svsk->sk_sk, skb);
                        return 0;
                }
                local_bh_enable();
-               skb_free_datagram(svsk->sk_sk, skb);
+               skb_free_datagram_locked(svsk->sk_sk, skb);
        } else {
                /* we can use it in-place */
                rqstp->rq_arg.head[0].iov_base = skb->data +
                        sizeof(struct udphdr);
                rqstp->rq_arg.head[0].iov_len = len;
                if (skb_checksum_complete(skb)) {
-                       skb_free_datagram(svsk->sk_sk, skb);
+                       skb_free_datagram_locked(svsk->sk_sk, skb);
                        return 0;
                }
                rqstp->rq_xprt_ctxt = skb;