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Date:   Thu, 6 Jun 2019 15:41:27 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Lee Jones <lee.jones@...aro.org>,
        Amelie DELAUNAY <amelie.delaunay@...com>
Cc:     Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        linux-stm32@...md-mailman.stormreply.com,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH v2] mfd: stmfx: Uninitialized variable in stmfx_irq_handler()

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@...cle.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

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