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authorDavid S. Miller <davem@davemloft.net>2014-04-11 20:15:36 (GMT)
committerDavid S. Miller <davem@davemloft.net>2014-04-11 20:15:36 (GMT)
commit676d23690fb62b5d51ba5d659935e9f7d9da9f8e (patch)
treef6fbceee43e05c724868153ca37b702fb5e43b8c /net/caif
parentad20d5f673898578f9d8a156d7a4c921f5ca4584 (diff)
net: Fix use after free by removing length arg from sk_data_ready callbacks.
Several spots in the kernel perform a sequence like: skb_queue_tail(&sk->s_receive_queue, skb); sk->sk_data_ready(sk, skb->len); But at the moment we place the SKB onto the socket receive queue it can be consumed and freed up. So this skb->len access is potentially to freed up memory. Furthermore, the skb->len can be modified by the consumer so it is possible that the value isn't accurate. And finally, no actual implementation of this callback actually uses the length argument. And since nobody actually cared about it's value, lots of call sites pass arbitrary values in such as '0' and even '1'. So just remove the length argument from the callback, that way there is no confusion whatsoever and all of these use-after-free cases get fixed as a side effect. Based upon a patch by Eric Dumazet and his suggestion to audit this issue tree-wide. Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/caif')
-rw-r--r--net/caif/caif_socket.c4
1 files changed, 1 insertions, 3 deletions
diff --git a/net/caif/caif_socket.c b/net/caif/caif_socket.c
index d6be3ed..e843709 100644
--- a/net/caif/caif_socket.c
+++ b/net/caif/caif_socket.c
@@ -124,7 +124,6 @@ static void caif_flow_ctrl(struct sock *sk, int mode)
static int caif_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
{
int err;
- int skb_len;
unsigned long flags;
struct sk_buff_head *list = &sk->sk_receive_queue;
struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
@@ -153,14 +152,13 @@ static int caif_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
* may be freed by other threads of control pulling packets
* from the queue.
*/
- skb_len = skb->len;
spin_lock_irqsave(&list->lock, flags);
if (!sock_flag(sk, SOCK_DEAD))
__skb_queue_tail(list, skb);
spin_unlock_irqrestore(&list->lock, flags);
if (!sock_flag(sk, SOCK_DEAD))
- sk->sk_data_ready(sk, skb_len);
+ sk->sk_data_ready(sk);
else
kfree_skb(skb);
return 0;

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