Ping?
On 06/19/2014 11:23 PM, Sasha Levin wrote:
> Right now userspace can pass a large chunk of data and the kernel
> will attempt to allocate all of it to copy it in from userspace.
>
> The problem is that there is no upper limit on the size userspace
> can pass. Right now userspace can even force a machine to run out
> of memory by forcing the kernel to allocate large chunks of memory.
>
> To avoid imposing a limit, instead of allocating the entire block,
> we can allocate just the size of the biggest frag possible and read
> it from userspace one frag at a time.
>
> Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
> ---
>
> ** WARNING: COMPLETELY UNTESTED ** (I don't have the hardware).
>
> net/nfc/llcp_commands.c | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/net/nfc/llcp_commands.c b/net/nfc/llcp_commands.c
> index a3ad69a..da68924 100644
> --- a/net/nfc/llcp_commands.c
> +++ b/net/nfc/llcp_commands.c
> @@ -727,27 +727,27 @@ int nfc_llcp_send_ui_frame(struct nfc_llcp_sock *sock, u8 ssap, u8 dsap,
> if (local == NULL)
> return -ENODEV;
>
> - msg_data = kzalloc(len, GFP_KERNEL);
> + remote_miu = sock->remote_miu > LLCP_MAX_MIU ?
> + local->remote_miu : sock->remote_miu;
> +
> + msg_data = kzalloc(remote_miu, GFP_KERNEL);
> if (msg_data == NULL)
> return -ENOMEM;
>
> - if (memcpy_fromiovec(msg_data, msg->msg_iov, len)) {
> - kfree(msg_data);
> - return -EFAULT;
> - }
> -
> remaining_len = len;
> msg_ptr = msg_data;
>
> do {
> - remote_miu = sock->remote_miu > LLCP_MAX_MIU ?
> - local->remote_miu : sock->remote_miu;
> -
> frag_len = min_t(size_t, remote_miu, remaining_len);
>
> pr_debug("Fragment %zd bytes remaining %zd",
> frag_len, remaining_len);
>
> + if (memcpy_fromiovec(msg_data, msg->msg_iov, frag_len)) {
> + kfree(msg_data);
> + return -EFAULT;
> + }
> +
> pdu = nfc_alloc_send_skb(sock->dev, &sock->sk, MSG_DONTWAIT,
> frag_len + LLCP_HEADER_SIZE, &err);
> if (pdu == NULL) {
>
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