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    Subject[PATCH 5.4 02/98] spi: bcm2835: Fix use-after-free on unbind
    Date
    From: Lukas Wunner <lukas@wunner.de>

    commit e1483ac030fb4c57734289742f1c1d38dca61e22 upstream

    bcm2835_spi_remove() accesses the driver's private data after calling
    spi_unregister_controller() even though that function releases the last
    reference on the spi_controller 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: f8043872e796 ("spi: add driver for BCM2835")
    Reported-by: Sascha Hauer <s.hauer@pengutronix.de>
    Reported-by: Florian Fainelli <f.fainelli@gmail.com>
    Signed-off-by: Lukas Wunner <lukas@wunner.de>
    Cc: <stable@vger.kernel.org> # v3.10+: 123456789abc: spi: Introduce device-managed SPI controller allocation
    Cc: <stable@vger.kernel.org> # v3.10+
    Cc: Vladimir Oltean <olteanv@gmail.com>
    Tested-by: Florian Fainelli <f.fainelli@gmail.com>
    Acked-by: Florian Fainelli <f.fainelli@gmail.com>
    Link: https://lore.kernel.org/r/ad66e0a0ad96feb848814842ecf5b6a4539ef35c.1605121038.git.lukas@wunner.de
    Signed-off-by: Mark Brown <broonie@kernel.org>
    [sudip: dev_err_probe() not yet available]
    Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/spi/spi-bcm2835.c | 18 ++++++------------
    1 file changed, 6 insertions(+), 12 deletions(-)

    --- a/drivers/spi/spi-bcm2835.c
    +++ b/drivers/spi/spi-bcm2835.c
    @@ -1264,7 +1264,7 @@ static int bcm2835_spi_probe(struct plat
    struct bcm2835_spi *bs;
    int err;

    - ctlr = spi_alloc_master(&pdev->dev, ALIGN(sizeof(*bs),
    + ctlr = devm_spi_alloc_master(&pdev->dev, ALIGN(sizeof(*bs),
    dma_get_cache_alignment()));
    if (!ctlr)
    return -ENOMEM;
    @@ -1284,23 +1284,19 @@ static int bcm2835_spi_probe(struct plat
    bs = spi_controller_get_devdata(ctlr);

    bs->regs = devm_platform_ioremap_resource(pdev, 0);
    - if (IS_ERR(bs->regs)) {
    - err = PTR_ERR(bs->regs);
    - goto out_controller_put;
    - }
    + if (IS_ERR(bs->regs))
    + return PTR_ERR(bs->regs);

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

    bs->irq = platform_get_irq(pdev, 0);
    - if (bs->irq <= 0) {
    - err = bs->irq ? bs->irq : -ENODEV;
    - goto out_controller_put;
    - }
    + if (bs->irq <= 0)
    + return bs->irq ? bs->irq : -ENODEV;

    clk_prepare_enable(bs->clk);

    @@ -1330,8 +1326,6 @@ static int bcm2835_spi_probe(struct plat

    out_clk_disable:
    clk_disable_unprepare(bs->clk);
    -out_controller_put:
    - spi_controller_put(ctlr);
    return err;
    }


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