[PATCH v2] mfd: stmfx: Uninitialized variable in stmfx_irq_handler()

Dan Carpenter
2019-06-06T12:41:27Z

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>
---
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;
--
2.20.1