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    Subject[34-longterm 169/209] IB/uverbs: Handle large number of entries in poll CQ
    Date
    From: Dan Carpenter <error27@gmail.com>

    =====================================================================
    | This is a commit scheduled for the next v2.6.34 longterm release. |
    | If you see a problem with using this for longterm, please comment.|
    =====================================================================

    commit 7182afea8d1afd432a17c18162cc3fd441d0da93 upstream.

    In ib_uverbs_poll_cq() code there is a potential integer overflow if
    userspace passes in a large cmd.ne. The calls to kmalloc() would
    allocate smaller buffers than intended, leading to memory corruption.
    There iss also an information leak if resp wasn't all used.
    Unprivileged userspace may call this function, although only if an
    RDMA device that uses this function is present.

    Fix this by copying CQ entries one at a time, which avoids the
    allocation entirely, and also by moving this copying into a function
    that makes sure to initialize all memory copied to userspace.

    Special thanks to Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
    for his help and advice.

    Signed-off-by: Dan Carpenter <error27@gmail.com>

    [ Monkey around with things a bit to avoid bad code generation by gcc
    when designated initializers are used. - Roland ]

    Signed-off-by: Roland Dreier <rolandd@cisco.com>
    Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
    ---
    drivers/infiniband/core/uverbs_cmd.c | 101 +++++++++++++++++++---------------
    1 files changed, 57 insertions(+), 44 deletions(-)

    diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
    index 6fcfbeb..abb8714 100644
    --- a/drivers/infiniband/core/uverbs_cmd.c
    +++ b/drivers/infiniband/core/uverbs_cmd.c
    @@ -891,68 +891,81 @@ out:
    return ret ? ret : in_len;
    }

    +static int copy_wc_to_user(void __user *dest, struct ib_wc *wc)
    +{
    + struct ib_uverbs_wc tmp;
    +
    + tmp.wr_id = wc->wr_id;
    + tmp.status = wc->status;
    + tmp.opcode = wc->opcode;
    + tmp.vendor_err = wc->vendor_err;
    + tmp.byte_len = wc->byte_len;
    + tmp.ex.imm_data = (__u32 __force) wc->ex.imm_data;
    + tmp.qp_num = wc->qp->qp_num;
    + tmp.src_qp = wc->src_qp;
    + tmp.wc_flags = wc->wc_flags;
    + tmp.pkey_index = wc->pkey_index;
    + tmp.slid = wc->slid;
    + tmp.sl = wc->sl;
    + tmp.dlid_path_bits = wc->dlid_path_bits;
    + tmp.port_num = wc->port_num;
    + tmp.reserved = 0;
    +
    + if (copy_to_user(dest, &tmp, sizeof tmp))
    + return -EFAULT;
    +
    + return 0;
    +}
    +
    ssize_t ib_uverbs_poll_cq(struct ib_uverbs_file *file,
    const char __user *buf, int in_len,
    int out_len)
    {
    struct ib_uverbs_poll_cq cmd;
    - struct ib_uverbs_poll_cq_resp *resp;
    + struct ib_uverbs_poll_cq_resp resp;
    + u8 __user *header_ptr;
    + u8 __user *data_ptr;
    struct ib_cq *cq;
    - struct ib_wc *wc;
    - int ret = 0;
    - int i;
    - int rsize;
    + struct ib_wc wc;
    + int ret;

    if (copy_from_user(&cmd, buf, sizeof cmd))
    return -EFAULT;

    - wc = kmalloc(cmd.ne * sizeof *wc, GFP_KERNEL);
    - if (!wc)
    - return -ENOMEM;
    -
    - rsize = sizeof *resp + cmd.ne * sizeof(struct ib_uverbs_wc);
    - resp = kmalloc(rsize, GFP_KERNEL);
    - if (!resp) {
    - ret = -ENOMEM;
    - goto out_wc;
    - }
    -
    cq = idr_read_cq(cmd.cq_handle, file->ucontext, 0);
    - if (!cq) {
    - ret = -EINVAL;
    - goto out;
    - }
    + if (!cq)
    + return -EINVAL;

    - resp->count = ib_poll_cq(cq, cmd.ne, wc);
    + /* we copy a struct ib_uverbs_poll_cq_resp to user space */
    + header_ptr = (void __user *)(unsigned long) cmd.response;
    + data_ptr = header_ptr + sizeof resp;

    - put_cq_read(cq);
    + memset(&resp, 0, sizeof resp);
    + while (resp.count < cmd.ne) {
    + ret = ib_poll_cq(cq, 1, &wc);
    + if (ret < 0)
    + goto out_put;
    + if (!ret)
    + break;
    +
    + ret = copy_wc_to_user(data_ptr, &wc);
    + if (ret)
    + goto out_put;

    - for (i = 0; i < resp->count; i++) {
    - resp->wc[i].wr_id = wc[i].wr_id;
    - resp->wc[i].status = wc[i].status;
    - resp->wc[i].opcode = wc[i].opcode;
    - resp->wc[i].vendor_err = wc[i].vendor_err;
    - resp->wc[i].byte_len = wc[i].byte_len;
    - resp->wc[i].ex.imm_data = (__u32 __force) wc[i].ex.imm_data;
    - resp->wc[i].qp_num = wc[i].qp->qp_num;
    - resp->wc[i].src_qp = wc[i].src_qp;
    - resp->wc[i].wc_flags = wc[i].wc_flags;
    - resp->wc[i].pkey_index = wc[i].pkey_index;
    - resp->wc[i].slid = wc[i].slid;
    - resp->wc[i].sl = wc[i].sl;
    - resp->wc[i].dlid_path_bits = wc[i].dlid_path_bits;
    - resp->wc[i].port_num = wc[i].port_num;
    + data_ptr += sizeof(struct ib_uverbs_wc);
    + ++resp.count;
    }

    - if (copy_to_user((void __user *) (unsigned long) cmd.response, resp, rsize))
    + if (copy_to_user(header_ptr, &resp, sizeof resp)) {
    ret = -EFAULT;
    + goto out_put;
    + }

    -out:
    - kfree(resp);
    + ret = in_len;

    -out_wc:
    - kfree(wc);
    - return ret ? ret : in_len;
    +out_put:
    + put_cq_read(cq);
    + return ret;
    }

    ssize_t ib_uverbs_req_notify_cq(struct ib_uverbs_file *file,
    --
    1.7.4.4


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