| Message ID | 1564563689-25863-1-git-send-email-yoshihiro.shimoda.uh@renesas.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Geert Uytterhoeven |
| Headers | show |
| Series | phy: renesas: rcar-gen3-usb2: Fix sysfs interface of "role" | expand |
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>
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;
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(-)