linux-kernel - [PATCH] staging: kpc2000: fix integer overflow with left shifts

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Message-Id: <20190618101554.31723-1-colin.king@canonical.com>
Date:   Tue, 18 Jun 2019 11:15:54 +0100
From:   Colin King <colin.king@...onical.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Simon Sandström <simon@...anor.nu>,
        devel@...verdev.osuosl.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] staging: kpc2000: fix integer overflow with left shifts

From: Colin Ian King <colin.king@...onical.com>

Currently there are several left shifts that are assigned to 64 bit
unsigned longs where a signed int 1 is being shifted, resulting in
an integer overflow.  Fix this bit using the BIT_ULL macro to perform
a 64 bit shift.  Also clean up an overly long statement.

Addresses-Coverity: ("Unintentional integer overflow")
Fixes: 7dc7967fc39a ("staging: kpc2000: add initial set of Daktronics drivers")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/staging/kpc2000/kpc2000/cell_probe.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/kpc2000/kpc2000/cell_probe.c b/drivers/staging/kpc2000/kpc2000/cell_probe.c
index 138d16bcf6e1..c124a836db27 100644
--- a/drivers/staging/kpc2000/kpc2000/cell_probe.c
+++ b/drivers/staging/kpc2000/kpc2000/cell_probe.c
@@ -238,7 +238,7 @@ int  kp2000_check_uio_irq(struct kp2000_device *pcard, u32 irq_num)
 {
 	u64 interrupt_active   =  readq(pcard->sysinfo_regs_base + REG_INTERRUPT_ACTIVE);
 	u64 interrupt_mask_inv = ~readq(pcard->sysinfo_regs_base + REG_INTERRUPT_MASK);
-	u64 irq_check_mask = (1 << irq_num);
+	u64 irq_check_mask = BIT_ULL(irq_num);
 
 	if (interrupt_active & irq_check_mask) { // if it's active (interrupt pending)
 		if (interrupt_mask_inv & irq_check_mask) {    // and if it's not masked off
@@ -257,7 +257,9 @@ irqreturn_t  kuio_handler(int irq, struct uio_info *uioinfo)
 		return IRQ_NONE;
 
 	if (kp2000_check_uio_irq(kudev->pcard, kudev->cte.irq_base_num)) {
-		writeq((1 << kudev->cte.irq_base_num), kudev->pcard->sysinfo_regs_base + REG_INTERRUPT_ACTIVE); // Clear the active flag
+		/* Clear the active flag */
+		writeq(BIT_ULL(kudev->cte.irq_base_num),
+		       kudev->pcard->sysinfo_regs_base + REG_INTERRUPT_ACTIVE);
 		return IRQ_HANDLED;
 	}
 	return IRQ_NONE;
@@ -273,9 +275,9 @@ int kuio_irqcontrol(struct uio_info *uioinfo, s32 irq_on)
 	mutex_lock(&pcard->sem);
 	mask = readq(pcard->sysinfo_regs_base + REG_INTERRUPT_MASK);
 	if (irq_on)
-		mask &= ~(1 << (kudev->cte.irq_base_num));
+		mask &= ~(BIT_ULL(kudev->cte.irq_base_num));
 	else
-		mask |= (1 << (kudev->cte.irq_base_num));
+		mask |= BIT_ULL(kudev->cte.irq_base_num);
 	writeq(mask, pcard->sysinfo_regs_base + REG_INTERRUPT_MASK);
 	mutex_unlock(&pcard->sem);
 
-- 
2.20.1