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SubjectRe: [PATCH v2] mfd: stmfx: Uninitialized variable in stmfx_irq_handler()
Date
On 6/6/19 2:41 PM, Dan Carpenter wrote:
> The problem is that on 64bit systems then we don't clear the higher
> bits of the "pending" variable. So when we do:
>
> ack = pending & ~BIT(STMFX_REG_IRQ_SRC_EN_GPIO);
> if (ack) {
>
> the if (ack) condition relies on uninitialized data. The fix it that
> I've changed "pending" from an unsigned long to a u32. I changed "n" as
> well, because that's a number in the 0-10 range and it fits easily
> inside an int. We do need to add a cast to "pending" when we use it in
> the for_each_set_bit() loop, but that doesn't cause a proble, it's
> fine.
>
> Fixes: 06252ade9156 ("mfd: Add ST Multi-Function eXpander (STMFX) core driver")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Acked-by: Amelie Delaunay <amelie.delaunay@st.com>

> ---
> v2: white space changes
>
> drivers/mfd/stmfx.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/mfd/stmfx.c b/drivers/mfd/stmfx.c
> index fe8efba2d45f..7c419c078688 100644
> --- a/drivers/mfd/stmfx.c
> +++ b/drivers/mfd/stmfx.c
> @@ -204,12 +204,10 @@ static struct irq_chip stmfx_irq_chip = {
> static irqreturn_t stmfx_irq_handler(int irq, void *data)
> {
> struct stmfx *stmfx = data;
> - unsigned long n, pending;
> - u32 ack;
> - int ret;
> + u32 pending, ack;
> + int n, ret;
>
> - ret = regmap_read(stmfx->map, STMFX_REG_IRQ_PENDING,
> - (u32 *)&pending);
> + ret = regmap_read(stmfx->map, STMFX_REG_IRQ_PENDING, &pending);
> if (ret)
> return IRQ_NONE;
>
> @@ -224,7 +222,7 @@ static irqreturn_t stmfx_irq_handler(int irq, void *data)
> return IRQ_NONE;
> }
>
> - for_each_set_bit(n, &pending, STMFX_REG_IRQ_SRC_MAX)
> + for_each_set_bit(n, (unsigned long *)&pending, STMFX_REG_IRQ_SRC_MAX)
> handle_nested_irq(irq_find_mapping(stmfx->irq_domain, n));
>
> return IRQ_HANDLED;
>
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