From: David Laight <David.Laight@ACULAB.COM>
To: 'Kars Mulder' <kerneldev@karsmulder.nl>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Pavel Machek <pavel@ucw.cz>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Kai-Heng Feng <kai.heng.feng@canonical.com>
Subject: RE: Writing to a const pointer: is this supposed to happen?
Date: Thu, 2 Jul 2020 07:55:27 +0000 [thread overview]
Message-ID: <32182d4126fd49dabac4091b7a6c89e7@AcuMS.aculab.com> (raw)
In-Reply-To: <1f2d-5efd1600-b3-caae120@315006>
From: Kars Mulder
> Sent: 02 July 2020 00:03
> On Saturday, June 27, 2020 12:24 CEST, David Laight wrote:
> > The code quoted (using strset()) is almost certainly wrong.
> > The caller is unlikely to expect the input be modified.
> > Since it doesn't fault the string must be in read-write memory.
>
> I tried writing a patch that avoids the writing-to-const-pointer issue
> by using the less intrusive sscanf function instead of strsep. It might
> avoid a potential bug when somebody wrongly assumes that a
> kernel_param_ops.set function will not write to its const char* argument.
Hmm... sscanf() is also horrid.
Surprisingly difficult to use correctly.
It is usually best to use strchr() (and maybe str[c]scn())
to parse strings.
For numbers use whatever the kernels current 'favourite' implementation
of strtoul() is called.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2020-07-02 7:55 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-22 11:35 Kars Mulder
2020-06-23 19:55 ` Pavel Machek
2020-06-24 12:34 ` Kars Mulder
2020-06-24 13:10 ` Greg Kroah-Hartman
2020-06-24 15:25 ` Kars Mulder
2020-06-27 10:24 ` David Laight
2020-07-01 23:03 ` Kars Mulder
2020-07-02 7:55 ` David Laight [this message]
2020-07-02 21:48 ` Kars Mulder
2020-07-03 8:13 ` David Laight
2020-07-03 13:23 ` Kars Mulder
2020-07-04 11:55 ` Pavel Machek
2020-07-05 21:53 ` [PATCH] usb: core: fix quirks_param_set() writing to a const pointer Kars Mulder
2020-07-06 10:34 ` Greg Kroah-Hartman
2020-07-06 12:57 ` Kars Mulder
2020-07-06 13:07 ` Greg Kroah-Hartman
2020-07-06 13:58 ` Kars Mulder
[not found] <CAHp75Ve4O+OmVttjhtKepFWwZLU6tFMx5vNpPVJdB58mcLFm3w@mail.gmail.com>
2020-07-04 20:32 ` Writing to a const pointer: is this supposed to happen? Kars Mulder
2020-07-04 20:54 ` Andy Shevchenko
2020-07-05 18:27 ` Kars Mulder
[not found] <CAHp75Vf9ygQ++DL4ETMy54d=x6oS1qqHLhfyh58f7JCVvM17yA@mail.gmail.com>
2020-07-05 19:38 ` Kars Mulder
[not found] <CAHp75Ve3m=UK9r2o8bDotQWQBLz-fV8CO_VcTmWjdLW1p5wE-w@mail.gmail.com>
2020-07-05 20:48 ` Kars Mulder
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=32182d4126fd49dabac4091b7a6c89e7@AcuMS.aculab.com \
--to=david.laight@aculab.com \
--cc=gregkh@linuxfoundation.org \
--cc=kai.heng.feng@canonical.com \
--cc=kerneldev@karsmulder.nl \
--cc=linux-kernel@vger.kernel.org \
--cc=pavel@ucw.cz \
/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
all inboxes | Powered by JetHome®