* phy-rcar-gen3-usb2: wrong parsing of role in role_store?
@ 2019-07-30 9:51 Pavel Machek
2019-07-30 10:08 ` Yoshihiro Shimoda
2019-08-01 18:51 ` [cip-dev] " Ben Hutchings
0 siblings, 2 replies; 3+ messages in thread
From: Pavel Machek @ 2019-07-30 9:51 UTC (permalink / raw)
To: yoshihiro.shimoda.uh, kishon, linux-renesas-soc, linux-kernel; +Cc: cip-dev
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Hi!
Code does strcmps, but does not actually check count. So AFAICT
writing "host-I-don't-want-I-need-peripheral" into the file will
succeed and turn it into host mode.
Also data beyond count in buf are going to be accessed.
Best regards,
Pavel
static ssize_t role_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct rcar_gen3_chan *ch = dev_get_drvdata(dev);
bool is_b_device;
enum phy_mode cur_mode, new_mode;
if (!ch->is_otg_channel || !rcar_gen3_is_any_rphy_initialized(ch))
return -EIO;
/* FIXME, this is wrong */
if (!strncmp(buf, "host", strlen("host")))
new_mode = PHY_MODE_USB_HOST;
else if (!strncmp(buf, "peripheral", strlen("peripheral")))
new_mode = PHY_MODE_USB_DEVICE;
else
return -EINVAL;
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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^ permalink raw reply [flat|nested] 3+ messages in thread
* RE: phy-rcar-gen3-usb2: wrong parsing of role in role_store?
2019-07-30 9:51 phy-rcar-gen3-usb2: wrong parsing of role in role_store? Pavel Machek
@ 2019-07-30 10:08 ` Yoshihiro Shimoda
2019-08-01 18:51 ` [cip-dev] " Ben Hutchings
1 sibling, 0 replies; 3+ messages in thread
From: Yoshihiro Shimoda @ 2019-07-30 10:08 UTC (permalink / raw)
To: Pavel Machek, kishon, linux-renesas-soc, linux-kernel; +Cc: cip-dev
Hi Pavel,
> From: Pavel Machek, Sent: Tuesday, July 30, 2019 6:52 PM
>
> Hi!
>
> Code does strcmps, but does not actually check count. So AFAICT
> writing "host-I-don't-want-I-need-peripheral" into the file will
> succeed and turn it into host mode.
>
> Also data beyond count in buf are going to be accessed.
Thank you for the report. I think the driver should use sysfs_streq() helper
instead of strncmp() on the sysfs function. So, I'll submit such a patch later.
Best regards,
Yoshihiro Shimoda
> Best regards,
> Pavel
>
> static ssize_t role_store(struct device *dev, struct device_attribute *attr,
> const char *buf, size_t count)
> {
> struct rcar_gen3_chan *ch = dev_get_drvdata(dev);
> bool is_b_device;
> enum phy_mode cur_mode, new_mode;
>
> if (!ch->is_otg_channel || !rcar_gen3_is_any_rphy_initialized(ch))
> return -EIO;
>
> /* FIXME, this is wrong */
> if (!strncmp(buf, "host", strlen("host")))
> new_mode = PHY_MODE_USB_HOST;
> else if (!strncmp(buf, "peripheral", strlen("peripheral")))
> new_mode = PHY_MODE_USB_DEVICE;
> else
> return -EINVAL;
>
>
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [cip-dev] phy-rcar-gen3-usb2: wrong parsing of role in role_store?
2019-07-30 9:51 phy-rcar-gen3-usb2: wrong parsing of role in role_store? Pavel Machek
2019-07-30 10:08 ` Yoshihiro Shimoda
@ 2019-08-01 18:51 ` Ben Hutchings
1 sibling, 0 replies; 3+ messages in thread
From: Ben Hutchings @ 2019-08-01 18:51 UTC (permalink / raw)
To: Pavel Machek, yoshihiro.shimoda.uh, kishon, linux-renesas-soc,
linux-kernel
Cc: cip-dev
On Tue, 2019-07-30 at 11:51 +0200, Pavel Machek wrote:
> Hi!
>
> Code does strcmps, but does not actually check count. So AFAICT
> writing "host-I-don't-want-I-need-peripheral" into the file will
> succeed and turn it into host mode.
I suspect the intent is to work without a trailing "\n", but you're
right that this parsing is rather lax.
> Also data beyond count in buf are going to be accessed.
All attribute writes should be going through kernfs_fop_write(), which
writes a null terminator at buf[count] before calling the write/store
function. (I don't know where that'ss documented though.) So I think
this is safe.
Ben.
> static ssize_t role_store(struct device *dev, struct device_attribute *attr,
> const char *buf, size_t count)
> {
> struct rcar_gen3_chan *ch = dev_get_drvdata(dev);
> bool is_b_device;
> enum phy_mode cur_mode, new_mode;
>
> if (!ch->is_otg_channel || !rcar_gen3_is_any_rphy_initialized(ch))
> return -EIO;
>
> /* FIXME, this is wrong */
> if (!strncmp(buf, "host", strlen("host")))
> new_mode = PHY_MODE_USB_HOST;
> else if (!strncmp(buf, "peripheral", strlen("peripheral")))
> new_mode = PHY_MODE_USB_DEVICE;
> else
> return -EINVAL;
>
>
> _______________________________________________
> cip-dev mailing list
> cip-dev@lists.cip-project.org
> https://lists.cip-project.org/mailman/listinfo/cip-dev
--
Ben Hutchings, Software Developer Codethink Ltd
https://www.codethink.co.uk/ Dale House, 35 Dale Street
Manchester, M1 2HF, United Kingdom
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2019-07-30 10:08 ` Yoshihiro Shimoda
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