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@denx.de Fixes: 9bb86777fb71 ("phy: rcar-gen3-usb2: add sysfs for usb role swap") Cc: stable@vger.kernel.org # v4.10+ Signed-off-by: Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com --- 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;
Hi Shimoda-san,
On Wed, Jul 31, 2019 at 11:04 AM Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com 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 pavel@denx.de Fixes: 9bb86777fb71 ("phy: rcar-gen3-usb2: add sysfs for usb role swap") Cc: stable@vger.kernel.org # v4.10+ Signed-off-by: Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com
Reviewed-by: Geert Uytterhoeven geert+renesas@glider.be
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.
Is that wat you mean? sysfs_streq() doesn't seem to check for NULL pointers.
Isn't the real reason that sysfs (kernfs) guarantees that the passed buffer is NUL-terminated?
Gr{oetje,eeting}s,
Geert
Hi Geert-san,
From: Geert Uytterhoeven, Sent: Wednesday, July 31, 2019 6:27 PM
Hi Shimoda-san,
On Wed, Jul 31, 2019 at 11:04 AM Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com 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 pavel@denx.de Fixes: 9bb86777fb71 ("phy: rcar-gen3-usb2: add sysfs for usb role swap") Cc: stable@vger.kernel.org # v4.10+ Signed-off-by: Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com
Reviewed-by: Geert Uytterhoeven geert+renesas@glider.be
Thank you for your review!
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.
Is that wat you mean? sysfs_streq() doesn't seem to check for NULL pointers.
Oops, sorry for unclear. I meant a NULL-terminated string, not NULL pointer.
Isn't the real reason that sysfs (kernfs) guarantees that the passed buffer is NUL-terminated?
I doesn't check in detail, but I assume so.
Best regards, Yoshihiro Shimoda
Gr{oetje,eeting}s,
Geert-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
Hi Shimoda-san,
On Wed, Jul 31, 2019 at 11:58 AM Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com wrote:
From: Geert Uytterhoeven, Sent: Wednesday, July 31, 2019 6:27 PM On Wed, Jul 31, 2019 at 11:04 AM Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com 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 pavel@denx.de Fixes: 9bb86777fb71 ("phy: rcar-gen3-usb2: add sysfs for usb role swap") Cc: stable@vger.kernel.org # v4.10+ Signed-off-by: Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com
Reviewed-by: Geert Uytterhoeven geert+renesas@glider.be
Thank you for your review!
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.
Is that wat you mean? sysfs_streq() doesn't seem to check for NULL pointers.
Oops, sorry for unclear. I meant a NULL-terminated string, not NULL pointer.
OK.
Isn't the real reason that sysfs (kernfs) guarantees that the passed buffer is NUL-terminated?
I doesn't check in detail, but I assume so.
I have checked that recently, so it is OK.
Gr{oetje,eeting}s,
Geert
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 pavel@denx.de Fixes: 9bb86777fb71 ("phy: rcar-gen3-usb2: add sysfs for usb role swap") Cc: stable@vger.kernel.org # v4.10+ Signed-off-by: Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com
Acked-by: Pavel Machek pavel@denx.de
linux-stable-mirror@lists.linaro.org
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Geert Uytterhoeven -
Pavel Machek -
Yoshihiro Shimoda