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From:   Laura Abbott <labbott@redhat.com>
To:     Linus Walleij <linus.walleij@linaro.org>,
        Kees Cook <keescook@chromium.org>,
        Patrice Chotard <patrice.chotard@st.com>
Cc:     Laura Abbott <labbott@redhat.com>, linux-gpio@vger.kernel.org,
        linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com
Subject: [PATCHv2 4/4] gpio: Remove VLA from stmpe driver
Date:   Thu, 15 Mar 2018 11:00:30 -0700
Message-Id: <20180315180030.20001-5-labbott@redhat.com>
In-Reply-To: <20180315180030.20001-1-labbott@redhat.com>
References: <20180315180030.20001-1-labbott@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The new challenge is to remove VLAs from the kernel
(see https://lkml.org/lkml/2018/3/7/621)

This patch replaces a VLA with an appropriate call to kmalloc_array.

Signed-off-by: Laura Abbott <labbott@redhat.com>
---
v2: Switch to GFP_KERNEL. There was some discussion about if we should
be doing the allocation at all but given a) the allocation is pretty
small and b) we can possibly take a mutex in a called function I think
this is fine.
---
 drivers/gpio/gpio-stmpe.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-stmpe.c b/drivers/gpio/gpio-stmpe.c
index f8d7d1cd8488..c2bb20ace6f5 100644
--- a/drivers/gpio/gpio-stmpe.c
+++ b/drivers/gpio/gpio-stmpe.c
@@ -369,10 +369,14 @@ static irqreturn_t stmpe_gpio_irq(int irq, void *dev)
 	struct stmpe *stmpe = stmpe_gpio->stmpe;
 	u8 statmsbreg;
 	int num_banks = DIV_ROUND_UP(stmpe->num_gpios, 8);
-	u8 status[num_banks];
+	u8 *status;
 	int ret;
 	int i;
 
+	status = kmalloc_array(num_banks, sizeof(*status), GFP_KERNEL);
+	if (!status)
+		return IRQ_NONE;
+
 	/*
 	 * the stmpe_block_read() call below, imposes to set statmsbreg
 	 * with the register located at the lowest address. As STMPE1600
@@ -424,6 +428,7 @@ static irqreturn_t stmpe_gpio_irq(int irq, void *dev)
 		}
 	}
 
+	kfree(status);
 	return IRQ_HANDLED;
 }
 
-- 
2.14.3