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authorEric Dumazet <eric.dumazet@gmail.com>2009-12-15 05:47:03 +0000
committerDavid S. Miller <davem@davemloft.net>2009-12-15 21:12:21 -0800
commit1a35ca80c1db7279c3c0655063f6d3490e399b17 (patch)
tree3ff2f23730c2bc6ea8af20232d02dad65ae63f0a /net/packet
parent81e839efc22361e3fa7ee36f99fd57c57d0d1871 (diff)
packet: dont call sleeping functions while holding rcu_read_lock()
commit 654d1f8a019dfa06d (packet: less dev_put() calls) introduced a problem, calling potentially sleeping functions from a rcu_read_lock() protected section. Fix this by releasing lock before the sock_wmalloc()/memcpy_fromiovec() calls. After skb allocation and copy from user space, we redo device lookup and appropriate tests. Reported-and-tested-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/packet')
-rw-r--r--net/packet/af_packet.c71
1 files changed, 31 insertions, 40 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 020562164b56..e0516a22be2e 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -415,7 +415,7 @@ static int packet_sendmsg_spkt(struct kiocb *iocb, struct socket *sock,
{
struct sock *sk = sock->sk;
struct sockaddr_pkt *saddr = (struct sockaddr_pkt *)msg->msg_name;
- struct sk_buff *skb;
+ struct sk_buff *skb = NULL;
struct net_device *dev;
__be16 proto = 0;
int err;
@@ -437,6 +437,7 @@ static int packet_sendmsg_spkt(struct kiocb *iocb, struct socket *sock,
*/
saddr->spkt_device[13] = 0;
+retry:
rcu_read_lock();
dev = dev_get_by_name_rcu(sock_net(sk), saddr->spkt_device);
err = -ENODEV;
@@ -456,58 +457,48 @@ static int packet_sendmsg_spkt(struct kiocb *iocb, struct socket *sock,
if (len > dev->mtu + dev->hard_header_len)
goto out_unlock;
- err = -ENOBUFS;
- skb = sock_wmalloc(sk, len + LL_RESERVED_SPACE(dev), 0, GFP_KERNEL);
-
- /*
- * If the write buffer is full, then tough. At this level the user
- * gets to deal with the problem - do your own algorithmic backoffs.
- * That's far more flexible.
- */
-
- if (skb == NULL)
- goto out_unlock;
-
- /*
- * Fill it in
- */
-
- /* FIXME: Save some space for broken drivers that write a
- * hard header at transmission time by themselves. PPP is the
- * notable one here. This should really be fixed at the driver level.
- */
- skb_reserve(skb, LL_RESERVED_SPACE(dev));
- skb_reset_network_header(skb);
-
- /* Try to align data part correctly */
- if (dev->header_ops) {
- skb->data -= dev->hard_header_len;
- skb->tail -= dev->hard_header_len;
- if (len < dev->hard_header_len)
- skb_reset_network_header(skb);
+ if (!skb) {
+ size_t reserved = LL_RESERVED_SPACE(dev);
+ unsigned int hhlen = dev->header_ops ? dev->hard_header_len : 0;
+
+ rcu_read_unlock();
+ skb = sock_wmalloc(sk, len + reserved, 0, GFP_KERNEL);
+ if (skb == NULL)
+ return -ENOBUFS;
+ /* FIXME: Save some space for broken drivers that write a hard
+ * header at transmission time by themselves. PPP is the notable
+ * one here. This should really be fixed at the driver level.
+ */
+ skb_reserve(skb, reserved);
+ skb_reset_network_header(skb);
+
+ /* Try to align data part correctly */
+ if (hhlen) {
+ skb->data -= hhlen;
+ skb->tail -= hhlen;
+ if (len < hhlen)
+ skb_reset_network_header(skb);
+ }
+ err = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
+ if (err)
+ goto out_free;
+ goto retry;
}
- /* Returns -EFAULT on error */
- err = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
+
skb->protocol = proto;
skb->dev = dev;
skb->priority = sk->sk_priority;
skb->mark = sk->sk_mark;
- if (err)
- goto out_free;
-
- /*
- * Now send it
- */
dev_queue_xmit(skb);
rcu_read_unlock();
return len;
-out_free:
- kfree_skb(skb);
out_unlock:
rcu_read_unlock();
+out_free:
+ kfree_skb(skb);
return err;
}