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    Subject[PATCH 4.9 001/175] spi: bcm2835aux: Fix use-after-free on unbind
    Date
    From: Lukas Wunner <lukas@wunner.de>

    [ Upstream commit e13ee6cc4781edaf8c7321bee19217e3702ed481 ]

    bcm2835aux_spi_remove() accesses the driver's private data after calling
    spi_unregister_master() even though that function releases the last
    reference on the spi_master and thereby frees the private data.

    Fix by switching over to the new devm_spi_alloc_master() helper which
    keeps the private data accessible until the driver has unbound.

    Fixes: b9dd3f6d4172 ("spi: bcm2835aux: Fix controller unregister order")
    Signed-off-by: Lukas Wunner <lukas@wunner.de>
    Cc: <stable@vger.kernel.org> # v4.4+: 5e844cc37a5c: spi: Introduce device-managed SPI controller allocation
    Cc: <stable@vger.kernel.org> # v4.4+: b9dd3f6d4172: spi: bcm2835aux: Fix controller unregister order
    Cc: <stable@vger.kernel.org> # v4.4+
    Link: https://lore.kernel.org/r/b290b06357d0c0bdee9cecc539b840a90630f101.1605121038.git.lukas@wunner.de
    Signed-off-by: Mark Brown <broonie@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/spi/spi-bcm2835aux.c | 18 ++++++------------
    1 file changed, 6 insertions(+), 12 deletions(-)

    --- a/drivers/spi/spi-bcm2835aux.c
    +++ b/drivers/spi/spi-bcm2835aux.c
    @@ -407,7 +407,7 @@ static int bcm2835aux_spi_probe(struct p
    unsigned long clk_hz;
    int err;

    - master = spi_alloc_master(&pdev->dev, sizeof(*bs));
    + master = devm_spi_alloc_master(&pdev->dev, sizeof(*bs));
    if (!master) {
    dev_err(&pdev->dev, "spi_alloc_master() failed\n");
    return -ENOMEM;
    @@ -439,30 +439,26 @@ static int bcm2835aux_spi_probe(struct p
    /* the main area */
    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    bs->regs = devm_ioremap_resource(&pdev->dev, res);
    - if (IS_ERR(bs->regs)) {
    - err = PTR_ERR(bs->regs);
    - goto out_master_put;
    - }
    + if (IS_ERR(bs->regs))
    + return PTR_ERR(bs->regs);

    bs->clk = devm_clk_get(&pdev->dev, NULL);
    if ((!bs->clk) || (IS_ERR(bs->clk))) {
    - err = PTR_ERR(bs->clk);
    dev_err(&pdev->dev, "could not get clk: %d\n", err);
    - goto out_master_put;
    + return PTR_ERR(bs->clk);
    }

    bs->irq = platform_get_irq(pdev, 0);
    if (bs->irq <= 0) {
    dev_err(&pdev->dev, "could not get IRQ: %d\n", bs->irq);
    - err = bs->irq ? bs->irq : -ENODEV;
    - goto out_master_put;
    + return bs->irq ? bs->irq : -ENODEV;
    }

    /* this also enables the HW block */
    err = clk_prepare_enable(bs->clk);
    if (err) {
    dev_err(&pdev->dev, "could not prepare clock: %d\n", err);
    - goto out_master_put;
    + return err;
    }

    /* just checking if the clock returns a sane value */
    @@ -495,8 +491,6 @@ static int bcm2835aux_spi_probe(struct p

    out_clk_disable:
    clk_disable_unprepare(bs->clk);
    -out_master_put:
    - spi_master_put(master);
    return err;
    }


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