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SubjectRe: Re: [PATCH] mmc: host: fix a possible null pointer access.
Date
On Wed, 18 Dec 2019 at 7:52 p.m., Ulf Hansson <ulf.hansson@linaro.org> wrote:
>>
>> 3419 if (host->slot &&
>> 3420 (mmc_can_gpio_cd(host->slot->mmc) ||
>> 3421 !mmc_card_is_removable(host->slot->mmc))) {
>> 3422 ret = clk_prepare_enable(host->biu_clk);
>> 3423 if (ret)
>> 3424 return ret;
>> 3425 }
>>
>> We previously assumed 'host->slot' could be null (see line 3419).
>>
>> The following situation is similar, so add a judgement.
>>
>> Signed-off-by: Pan Zhang <zhangpan26@huawei.com>
>> ---
>> drivers/mmc/host/dw_mmc.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>> index fc9d4d0..8e27c52 100644
>> --- a/drivers/mmc/host/dw_mmc.c
>> +++ b/drivers/mmc/host/dw_mmc.c
>> @@ -3454,7 +3454,7 @@ int dw_mci_runtime_resume(struct device *dev)
>> mci_writel(host, CTRL, SDMMC_CTRL_INT_ENABLE);
>>
>>
>> - if (host->slot->mmc->pm_flags & MMC_PM_KEEP_POWER)
>> + if (host->slot && (host->slot->mmc->pm_flags &
>> + MMC_PM_KEEP_POWER))
>> dw_mci_set_ios(host->slot->mmc,
>> &host->slot->mmc->ios);

>This shouldn't be a problem as the ->runtime_resume() callback can't be invoked, unless there is a slot.

>>
>> /* Force setup bus to guarantee available clock output */
>> --
>> 2.7.4
>>

If so, there is no need to assume host->slot pointer previously(line 3419)?

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