linux-kernel - [PATCH][next] gpio: xilinx: Fix potential integer overflow on shift of a u32 int

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Message-Id: <20210513085227.54392-1-colin.king@canonical.com>
Date:   Thu, 13 May 2021 09:52:27 +0100
From:   Colin King <colin.king@...onical.com>
To:     Shubhrajyoti Datta <shubhrajyoti.datta@...inx.com>,
        Srinivas Neeli <srinivas.neeli@...inx.com>,
        Michal Simek <michal.simek@...inx.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-gpio@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH][next] gpio: xilinx: Fix potential integer overflow on shift of a u32 int

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

The left shift of the u32 integer v is evaluated using 32 bit
arithmetic and then assigned to a u64 integer. There are cases
where v will currently overflow on the shift. Avoid this by
casting it to unsigned long (same type as map[]) before shifting
it.

Addresses-Coverity: ("Unintentional integer overflow")
Fixes: 02b3f84d9080 ("gpio: xilinx: Switch to use bitmap APIs")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/gpio/gpio-xilinx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-xilinx.c b/drivers/gpio/gpio-xilinx.c
index 109b32104867..164a3a5a9393 100644
--- a/drivers/gpio/gpio-xilinx.c
+++ b/drivers/gpio/gpio-xilinx.c
@@ -99,7 +99,7 @@ static inline void xgpio_set_value32(unsigned long *map, int bit, u32 v)
 	const unsigned long offset = (bit % BITS_PER_LONG) & BIT(5);
 
 	map[index] &= ~(0xFFFFFFFFul << offset);
-	map[index] |= v << offset;
+	map[index] |= (unsigned long)v << offset;
 }
 
 static inline int xgpio_regoffset(struct xgpio_instance *chip, int ch)
-- 
2.30.2