linux-kernel - Re: [PATCH] mfd: stmfx: Fix an endian bug in stmfx_irq

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Message-ID: <20190618081645.GM16364@dell>
Date:   Tue, 18 Jun 2019 09:16:45 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Amelie Delaunay <amelie.delaunay@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] mfd: stmfx: Fix an endian bug in stmfx_irq_handler()

On Mon, 17 Jun 2019, Dan Carpenter wrote:

> It's not okay to cast a "u32 *" to "unsigned long *" when you are
> doing a for_each_set_bit() loop because that will break on big
> endian systems.
> 
> Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>

Ideally we can get a review too.

> Fixes: 386145601b82 ("mfd: stmfx: Uninitialized variable in stmfx_irq_handler()")
> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
> ---
>  drivers/mfd/stmfx.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mfd/stmfx.c b/drivers/mfd/stmfx.c
> index 7c419c078688..857991cb3cbb 100644
> --- a/drivers/mfd/stmfx.c
> +++ b/drivers/mfd/stmfx.c
> @@ -204,6 +204,7 @@ static struct irq_chip stmfx_irq_chip = {
>  static irqreturn_t stmfx_irq_handler(int irq, void *data)
>  {
>  	struct stmfx *stmfx = data;
> +	unsigned long bits;
>  	u32 pending, ack;
>  	int n, ret;
>  
> @@ -222,7 +223,8 @@ static irqreturn_t stmfx_irq_handler(int irq, void *data)
>  			return IRQ_NONE;
>  	}
>  
> -	for_each_set_bit(n, (unsigned long *)&pending, STMFX_REG_IRQ_SRC_MAX)
> +	bits = pending;
> +	for_each_set_bit(n, &bits, STMFX_REG_IRQ_SRC_MAX)
>  		handle_nested_irq(irq_find_mapping(stmfx->irq_domain, n));
>  
>  	return IRQ_HANDLED;

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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