From: Ben Hutchings <ben.hutchings@codethink.co.uk>
To: Pavel Machek <pavel@denx.de>,
yoshihiro.shimoda.uh@renesas.com, kishon@ti.com,
linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: cip-dev@lists.cip-project.org
Subject: Re: [cip-dev] phy-rcar-gen3-usb2: wrong parsing of role in role_store?
Date: Thu, 01 Aug 2019 19:51:02 +0100 [thread overview]
Message-ID: <ffe639374bd93fe76f4aed19883640fefebd08f4.camel@codethink.co.uk> (raw)
In-Reply-To: <20190730095140.GA29609@amd>
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
prev parent reply other threads:[~2019-08-01 18:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
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 [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ffe639374bd93fe76f4aed19883640fefebd08f4.camel@codethink.co.uk \
--to=ben.hutchings@codethink.co.uk \
--cc=cip-dev@lists.cip-project.org \
--cc=kishon@ti.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-renesas-soc@vger.kernel.org \
--cc=pavel@denx.de \
--cc=yoshihiro.shimoda.uh@renesas.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).