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 <[email protected]>
Fixes: 9bb86777fb71 ("phy: rcar-gen3-usb2: add sysfs for usb role swap")
Cc: <[email protected]> # v4.10+
Signed-off-by: Yoshihiro Shimoda <[email protected]>
---
Just a record. The role_store() doesn't need to check the count because
the sysfs_streq() checks the first argument is NULL or not.
On "if (sysfs_streq(buf, "host"))"
Example 1: echo ho > role
--> In this case, the count is 3 and the buf has "ho" + NULL.
So, the third character differs between NULL and 's'.
Example 2: echo host-is-not-used > role
--> In this case, the count is 17 and the buf has "host-is-not-used" + NULL.
So, the fifth character differs between '-' and NULL.
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 1322185..cc18970 100644
--- a/drivers/phy/renesas/phy-rcar-gen3-usb2.c
+++ b/drivers/phy/renesas/phy-rcar-gen3-usb2.c
@@ -20,6 +20,7 @@
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/regulator/consumer.h>
+#include <linux/string.h>
#include <linux/usb/of.h>
#include <linux/workqueue.h>
@@ -317,9 +318,9 @@ static ssize_t role_store(struct device *dev, struct device_attribute *attr,
if (!ch->is_otg_channel || !rcar_gen3_is_any_rphy_initialized(ch))
return -EIO;
- if (!strncmp(buf, "host", strlen("host")))
+ if (sysfs_streq(buf, "host"))
new_mode = PHY_MODE_USB_HOST;
- else if (!strncmp(buf, "peripheral", strlen("peripheral")))
+ else if (sysfs_streq(buf, "peripheral"))
new_mode = PHY_MODE_USB_DEVICE;
else
return -EINVAL;
--
2.7.4
On Wed 2019-07-31 18:01:29, Yoshihiro Shimoda wrote:
> 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 <[email protected]>
> Fixes: 9bb86777fb71 ("phy: rcar-gen3-usb2: add sysfs for usb role swap")
> Cc: <[email protected]> # v4.10+
> Signed-off-by: Yoshihiro Shimoda <[email protected]>
Acked-by: Pavel Machek <[email protected]>
--
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