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    Subject[PATCH 5.10 642/717] spi: spi-sh: Fix use-after-free on unbind
    Date
    From: Lukas Wunner <lukas@wunner.de>

    commit e77df3eca12be4b17f13cf9f215cff248c57d98f upstream.

    spi_sh_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: 680c1305e259 ("spi/spi_sh: use spi_unregister_master instead of spi_master_put in remove path")
    Signed-off-by: Lukas Wunner <lukas@wunner.de>
    Cc: <stable@vger.kernel.org> # v3.0+: 5e844cc37a5c: spi: Introduce device-managed SPI controller allocation
    Cc: <stable@vger.kernel.org> # v3.0+
    Cc: Axel Lin <axel.lin@ingics.com>
    Link: https://lore.kernel.org/r/6d97628b536baf01d5e3e39db61108f84d44c8b2.1607286887.git.lukas@wunner.de
    Signed-off-by: Mark Brown <broonie@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/spi/spi-sh.c | 13 ++++---------
    1 file changed, 4 insertions(+), 9 deletions(-)

    --- a/drivers/spi/spi-sh.c
    +++ b/drivers/spi/spi-sh.c
    @@ -440,7 +440,7 @@ static int spi_sh_probe(struct platform_
    if (irq < 0)
    return irq;

    - master = spi_alloc_master(&pdev->dev, sizeof(struct spi_sh_data));
    + master = devm_spi_alloc_master(&pdev->dev, sizeof(struct spi_sh_data));
    if (master == NULL) {
    dev_err(&pdev->dev, "spi_alloc_master error.\n");
    return -ENOMEM;
    @@ -458,16 +458,14 @@ static int spi_sh_probe(struct platform_
    break;
    default:
    dev_err(&pdev->dev, "No support width\n");
    - ret = -ENODEV;
    - goto error1;
    + return -ENODEV;
    }
    ss->irq = irq;
    ss->master = master;
    ss->addr = devm_ioremap(&pdev->dev, res->start, resource_size(res));
    if (ss->addr == NULL) {
    dev_err(&pdev->dev, "ioremap error.\n");
    - ret = -ENOMEM;
    - goto error1;
    + return -ENOMEM;
    }
    INIT_LIST_HEAD(&ss->queue);
    spin_lock_init(&ss->lock);
    @@ -477,7 +475,7 @@ static int spi_sh_probe(struct platform_
    ret = request_irq(irq, spi_sh_irq, 0, "spi_sh", ss);
    if (ret < 0) {
    dev_err(&pdev->dev, "request_irq error\n");
    - goto error1;
    + return ret;
    }

    master->num_chipselect = 2;
    @@ -496,9 +494,6 @@ static int spi_sh_probe(struct platform_

    error3:
    free_irq(irq, ss);
    - error1:
    - spi_master_put(master);
    -
    return ret;
    }


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