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    Subject[PATCH 4.9 36/46] uio: Fix an Oops on load
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

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

    From: Dan Carpenter <dan.carpenter@oracle.com>

    commit 432798195bbce1f8cd33d1c0284d0538835e25fb upstream.

    I was trying to solve a double free but I introduced a more serious
    NULL dereference bug. The problem is that if there is an IRQ which
    triggers immediately, then we need "info->uio_dev" but it's not set yet.

    This patch puts the original initialization back to how it was and just
    sets info->uio_dev to NULL on the error path so it should solve both
    the Oops and the double free.

    Fixes: f019f07ecf6a ("uio: potential double frees if __uio_register_device() fails")
    Reported-by: Mathias Thore <Mathias.Thore@infinera.com>
    Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
    Cc: stable <stable@vger.kernel.org>
    Tested-by: Mathias Thore <Mathias.Thore@infinera.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/uio/uio.c | 7 +++++--
    1 file changed, 5 insertions(+), 2 deletions(-)

    --- a/drivers/uio/uio.c
    +++ b/drivers/uio/uio.c
    @@ -850,6 +850,8 @@ int __uio_register_device(struct module
    if (ret)
    goto err_uio_dev_add_attributes;

    + info->uio_dev = idev;
    +
    if (info->irq && (info->irq != UIO_IRQ_CUSTOM)) {
    /*
    * Note that we deliberately don't use devm_request_irq
    @@ -861,11 +863,12 @@ int __uio_register_device(struct module
    */
    ret = request_irq(info->irq, uio_interrupt,
    info->irq_flags, info->name, idev);
    - if (ret)
    + if (ret) {
    + info->uio_dev = NULL;
    goto err_request_irq;
    + }
    }

    - info->uio_dev = idev;
    return 0;

    err_request_irq:

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