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

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Message-ID: <m237gwcec4.fsf@baylibre.com>
Date:   Fri, 06 Jan 2017 09:01:31 -0800
From:   Kevin Hilman <khilman@...libre.com>
To:     Heinrich Schuchardt <xypron.glpk@....de>
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        Carlo Caione <carlo@...one.org>, linux-mmc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] MMC: meson: avoid possible NULL dereference

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,

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) {