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net: fix sk_forward_alloc corruption

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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>
This commit is contained in:
Eric Dumazet 2009-10-30 05:03:53 +00:00 committed by David S. Miller
parent 63ca2d74ea
commit 9d410c7960
5 changed files with 18 additions and 12 deletions
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2
include/linux/skbuff.h
View File

@ -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,

10
net/core/datagram.c
View File

@ -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);

4
net/ipv4/udp.c
View File

@ -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;

4
net/ipv6/udp.c
View File

@ -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;

10
net/sunrpc/svcsock.c
View File

@ -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;