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    Subject[PATCH 5.15 209/779] spi: Fix simplification of devm_spi_register_controller
    Date
    From: Yang Yingliang <yangyingliang@huawei.com>

    [ Upstream commit 43cc5a0afe4184a7fafe1eba32b5a11bb69c9ce0 ]

    This reverts commit 59ebbe40fb51 ("spi: simplify
    devm_spi_register_controller").

    If devm_add_action() fails in devm_add_action_or_reset(),
    devm_spi_unregister() will be called, it decreases the
    refcount of 'ctlr->dev' to 0, then it will cause uaf in
    the drivers that calling spi_put_controller() in error path.

    Fixes: 59ebbe40fb51 ("spi: simplify devm_spi_register_controller")
    Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
    Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
    Link: https://lore.kernel.org/r/20220712135504.1055688-1-yangyingliang@huawei.com
    Signed-off-by: Mark Brown <broonie@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/spi/spi.c | 19 ++++++++++++++-----
    1 file changed, 14 insertions(+), 5 deletions(-)

    diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
    index d0bbf8f9414d..556d65af5e23 100644
    --- a/drivers/spi/spi.c
    +++ b/drivers/spi/spi.c
    @@ -2949,9 +2949,9 @@ int spi_register_controller(struct spi_controller *ctlr)
    }
    EXPORT_SYMBOL_GPL(spi_register_controller);

    -static void devm_spi_unregister(void *ctlr)
    +static void devm_spi_unregister(struct device *dev, void *res)
    {
    - spi_unregister_controller(ctlr);
    + spi_unregister_controller(*(struct spi_controller **)res);
    }

    /**
    @@ -2970,13 +2970,22 @@ static void devm_spi_unregister(void *ctlr)
    int devm_spi_register_controller(struct device *dev,
    struct spi_controller *ctlr)
    {
    + struct spi_controller **ptr;
    int ret;

    + ptr = devres_alloc(devm_spi_unregister, sizeof(*ptr), GFP_KERNEL);
    + if (!ptr)
    + return -ENOMEM;
    +
    ret = spi_register_controller(ctlr);
    - if (ret)
    - return ret;
    + if (!ret) {
    + *ptr = ctlr;
    + devres_add(dev, ptr);
    + } else {
    + devres_free(ptr);
    + }

    - return devm_add_action_or_reset(dev, devm_spi_unregister, ctlr);
    + return ret;
    }
    EXPORT_SYMBOL_GPL(devm_spi_register_controller);

    --
    2.35.1


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