linux-kernel - Re: [PATCH 1/1] MMC: meson: avoid possible NULL dereference

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Date:   Tue, 10 Jan 2017 16:38:30 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Kevin Hilman <khilman@...libre.com>,
        Heinrich Schuchardt <xypron.glpk@....de>
Cc:     Carlo Caione <carlo@...one.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        linux-amlogic@...ts.infradead.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] MMC: meson: avoid possible NULL dereference

On 6 January 2017 at 18:01, Kevin Hilman <khilman@...libre.com> wrote:
> Heinrich Schuchardt <xypron.glpk@....de> writes:
>
>> No actual segmentation faults were observed but the coding is
>> at least inconsistent.
>>
>> irqreturn_t meson_mmc_irq():
>>
>> We should not dereference host before checking it.
>>
>> meson_mmc_irq_thread():
>>
>> If cmd or mrq are NULL we should not dereference them after
>> writing a warning.
>>
>> Fixes: 51c5d8447bd7 MMC: meson: initial support for GX platforms
>> Signed-off-by: Heinrich Schuchardt <xypron.glpk@....de>
>
> Acked-by: Kevin Hilman <khilman@...libre.com>
>
> Ulf, I assume you can pick this up directly for v4.10-rc?

Thanks, applied for fixes!

Kind regards
Uffe


>
> Thanks,
>
> Kevin
>
>> ---
>>  drivers/mmc/host/meson-gx-mmc.c | 8 +++++---
>>  1 file changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
>> index b352760c041e..09739352834c 100644
>> --- a/drivers/mmc/host/meson-gx-mmc.c
>> +++ b/drivers/mmc/host/meson-gx-mmc.c
>> @@ -578,13 +578,15 @@ static irqreturn_t meson_mmc_irq(int irq, void *dev_id)
>>  {
>>       struct meson_host *host = dev_id;
>>       struct mmc_request *mrq;
>> -     struct mmc_command *cmd = host->cmd;
>> +     struct mmc_command *cmd;
>>       u32 irq_en, status, raw_status;
>>       irqreturn_t ret = IRQ_HANDLED;
>>
>>       if (WARN_ON(!host))
>>               return IRQ_NONE;
>>
>> +     cmd = host->cmd;
>> +
>>       mrq = host->mrq;
>>
>>       if (WARN_ON(!mrq))
>> @@ -670,10 +672,10 @@ static irqreturn_t meson_mmc_irq_thread(int irq, void *dev_id)
>>       int ret = IRQ_HANDLED;
>>
>>       if (WARN_ON(!mrq))
>> -             ret = IRQ_NONE;
>> +             return IRQ_NONE;
>>
>>       if (WARN_ON(!cmd))
>> -             ret = IRQ_NONE;
>> +             return IRQ_NONE;
>>
>>       data = cmd->data;
>>       if (data) {