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    Subject[PATCH 4.19 351/639] mmc: core: fix possible use after free of host
    Date
    From: Pan Bian <bianpan2016@163.com>

    [ Upstream commit 8e1943af2986db42bee2b8dddf49a36cdb2e9219 ]

    In the function mmc_alloc_host, the function put_device is called to
    release allocated resources when mmc_gpio_alloc fails. Finally, the
    function pointed by host->class_dev.class->dev_release (i.e.,
    mmc_host_classdev_release) is used to release resources including the
    host structure. However, after put_device, host is used and released
    again. Resulting in a use-after-free bug.

    Fixes: 1ed217194488 ("mmc: core: fix error path in mmc_host_alloc")
    Signed-off-by: Pan Bian <bianpan2016@163.com>
    Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/mmc/core/host.c | 2 --
    1 file changed, 2 deletions(-)

    diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
    index f57f5de542064..dd1c14d8f6863 100644
    --- a/drivers/mmc/core/host.c
    +++ b/drivers/mmc/core/host.c
    @@ -385,8 +385,6 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev)

    if (mmc_gpio_alloc(host)) {
    put_device(&host->class_dev);
    - ida_simple_remove(&mmc_host_ida, host->index);
    - kfree(host);
    return NULL;
    }

    --
    2.20.1


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