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    Subject[PATCH 4.3 29/71] tcp: fix potential huge kmalloc() calls in TCP_REPAIR
    Date
    4.3-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Eric Dumazet <edumazet@google.com>

    [ Upstream commit 5d4c9bfbabdb1d497f21afd81501e5c54b0c85d9 ]

    tcp_send_rcvq() is used for re-injecting data into tcp receive queue.

    Problems :

    - No check against size is performed, allowed user to fool kernel in
    attempting very large memory allocations, eventually triggering
    OOM when memory is fragmented.

    - In case of fault during the copy we do not return correct errno.

    Lets use alloc_skb_with_frags() to cook optimal skbs.

    Fixes: 292e8d8c8538 ("tcp: Move rcvq sending to tcp_input.c")
    Fixes: c0e88ff0f256 ("tcp: Repair socket queues")
    Signed-off-by: Eric Dumazet <edumazet@google.com>
    Cc: Pavel Emelyanov <xemul@parallels.com>
    Acked-by: Pavel Emelyanov <xemul@parallels.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    net/ipv4/tcp_input.c | 22 +++++++++++++++++++---
    1 file changed, 19 insertions(+), 3 deletions(-)

    --- a/net/ipv4/tcp_input.c
    +++ b/net/ipv4/tcp_input.c
    @@ -4457,19 +4457,34 @@ static int __must_check tcp_queue_rcv(st
    int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size)
    {
    struct sk_buff *skb;
    + int err = -ENOMEM;
    + int data_len = 0;
    bool fragstolen;

    if (size == 0)
    return 0;

    - skb = alloc_skb(size, sk->sk_allocation);
    + if (size > PAGE_SIZE) {
    + int npages = min_t(size_t, size >> PAGE_SHIFT, MAX_SKB_FRAGS);
    +
    + data_len = npages << PAGE_SHIFT;
    + size = data_len + (size & ~PAGE_MASK);
    + }
    + skb = alloc_skb_with_frags(size - data_len, data_len,
    + PAGE_ALLOC_COSTLY_ORDER,
    + &err, sk->sk_allocation);
    if (!skb)
    goto err;

    + skb_put(skb, size - data_len);
    + skb->data_len = data_len;
    + skb->len = size;
    +
    if (tcp_try_rmem_schedule(sk, skb, skb->truesize))
    goto err_free;

    - if (memcpy_from_msg(skb_put(skb, size), msg, size))
    + err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, size);
    + if (err)
    goto err_free;

    TCP_SKB_CB(skb)->seq = tcp_sk(sk)->rcv_nxt;
    @@ -4485,7 +4500,8 @@ int tcp_send_rcvq(struct sock *sk, struc
    err_free:
    kfree_skb(skb);
    err:
    - return -ENOMEM;
    + return err;
    +
    }

    static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)



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