[PATCH 4.14 247/267] phy: renesas: rcar-gen3-usb2: Fix sysfs interface of "role"

[Greg Kroah-Hartman]

From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>

[ Upstream commit 4bd5ead82d4b877ebe41daf95f28cda53205b039 ]

Since the role_store() uses strncmp(), it's possible to refer
out-of-memory if the sysfs data size is smaller than strlen("host").
This patch fixes it by using sysfs_streq() instead of strncmp().

Reported-by: Pavel Machek <pavel@xxxxxxx>
Fixes: 9bb86777fb71 ("phy: rcar-gen3-usb2: add sysfs for usb role swap")
Cc: <stable@xxxxxxxxxxxxxxx> # v4.10+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Acked-by: Pavel Machek <pavel@xxxxxxx>
Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/phy/renesas/phy-rcar-gen3-usb2.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/renesas/phy-rcar-gen3-usb2.c b/drivers/phy/renesas/phy-rcar-gen3-usb2.c
index 7f5e36bfeee8d..f8c7ce89d8d73 100644
--- a/drivers/phy/renesas/phy-rcar-gen3-usb2.c
+++ b/drivers/phy/renesas/phy-rcar-gen3-usb2.c
@@ -22,6 +22,7 @@
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
+#include <linux/string.h>
 #include <linux/workqueue.h>
 
 /******* USB2.0 Host registers (original offset is +0x200) *******/
@@ -234,9 +235,9 @@ static ssize_t role_store(struct device *dev, struct device_attribute *attr,
 	 */
 	is_b_device = rcar_gen3_check_id(ch);
 	is_host = rcar_gen3_is_host(ch);
-	if (!strncmp(buf, "host", strlen("host")))
+	if (sysfs_streq(buf, "host"))
 		new_mode_is_host = true;
-	else if (!strncmp(buf, "peripheral", strlen("peripheral")))
+	else if (sysfs_streq(buf, "peripheral"))
 		new_mode_is_host = false;
 	else
 		return -EINVAL;
-- 
2.20.1