From: Mimi Zohar <zohar@linux.ibm.com>
To: David Laight <David.Laight@ACULAB.COM>,
'Markus Elfring' <Markus.Elfring@web.de>,
"linux-integrity@vger.kernel.org"
<linux-integrity@vger.kernel.org>,
"linux-security-module@vger.kernel.org"
<linux-security-module@vger.kernel.org>,
Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
James Morris <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
"kernel-janitors@vger.kernel.org"
<kernel-janitors@vger.kernel.org>
Subject: Re: [PATCH] ima: Replace two seq_printf() calls by seq_puts() in ima_show_template_data_ascii()
Date: Wed, 03 Jul 2019 11:14:39 +0000 [thread overview]
Message-ID: <1562152479.4774.18.camel@linux.ibm.com> (raw)
In-Reply-To: <d94bfdb9d53b46059787b9bdd10c5919@AcuMS.aculab.com>
On Wed, 2019-07-03 at 09:16 +0000, David Laight wrote:
> > diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
> > index 9fe0ef7f91e2..05636e9b19b1 100644
> > --- a/security/integrity/ima/ima_template_lib.c
> > +++ b/security/integrity/ima/ima_template_lib.c
> > @@ -74,7 +74,7 @@ static void ima_show_template_data_ascii(struct seq_file *m,
> > case DATA_FMT_DIGEST_WITH_ALGO:
> > buf_ptr = strnchr(field_data->data, buflen, ':');
> > if (buf_ptr != field_data->data)
> > - seq_printf(m, "%s", field_data->data);
> > + seq_puts(m, field_data->data);
> >
> > /* skip ':' and '\0' */
> > buf_ptr += 2;
>
> That code looks highly suspect!
> It uses a bounded scan then assumes a '\0' terminated string.
> It then adds 2 to a potentially NULL pointer.
The code here is used for displaying the IMA measurement list, that
the kernel itself created. Protecting the in kernel memory from
attack is a different problem. Refer to Igor Stoppa's write once
memory pools.
Mimi
WARNING: multiple messages have this Message-ID (diff)
From: Mimi Zohar <zohar@linux.ibm.com>
To: David Laight <David.Laight@ACULAB.COM>,
"'Markus Elfring'" <Markus.Elfring@web.de>,
"linux-integrity@vger.kernel.org"
<linux-integrity@vger.kernel.org>,
"linux-security-module@vger.kernel.org"
<linux-security-module@vger.kernel.org>,
Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
James Morris <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
"kernel-janitors@vger.kernel.org"
<kernel-janitors@vger.kernel.org>
Subject: Re: [PATCH] ima: Replace two seq_printf() calls by seq_puts() in ima_show_template_data_ascii()
Date: Wed, 03 Jul 2019 07:14:39 -0400 [thread overview]
Message-ID: <1562152479.4774.18.camel@linux.ibm.com> (raw)
In-Reply-To: <d94bfdb9d53b46059787b9bdd10c5919@AcuMS.aculab.com>
On Wed, 2019-07-03 at 09:16 +0000, David Laight wrote:
> > diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
> > index 9fe0ef7f91e2..05636e9b19b1 100644
> > --- a/security/integrity/ima/ima_template_lib.c
> > +++ b/security/integrity/ima/ima_template_lib.c
> > @@ -74,7 +74,7 @@ static void ima_show_template_data_ascii(struct seq_file *m,
> > case DATA_FMT_DIGEST_WITH_ALGO:
> > buf_ptr = strnchr(field_data->data, buflen, ':');
> > if (buf_ptr != field_data->data)
> > - seq_printf(m, "%s", field_data->data);
> > + seq_puts(m, field_data->data);
> >
> > /* skip ':' and '\0' */
> > buf_ptr += 2;
>
> That code looks highly suspect!
> It uses a bounded scan then assumes a '\0' terminated string.
> It then adds 2 to a potentially NULL pointer.
The code here is used for displaying the IMA measurement list, that
the kernel itself created. Protecting the in kernel memory from
attack is a different problem. Refer to Igor Stoppa's write once
memory pools.
Mimi
next prev parent reply other threads:[~2019-07-03 11:14 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-02 19:00 [PATCH] ima: Replace two seq_printf() calls by seq_puts() in ima_show_template_data_ascii() Markus Elfring
2019-07-02 19:00 ` Markus Elfring
2019-07-02 19:00 ` Markus Elfring
2019-07-02 19:00 ` Markus Elfring
2019-07-02 19:00 ` Markus Elfring
2019-07-02 19:00 ` Markus Elfring
2019-07-02 19:00 ` Markus Elfring
2019-07-02 19:00 ` Markus Elfring
2019-07-03 9:16 ` David Laight
2019-07-03 9:16 ` David Laight
2019-07-03 9:33 ` Markus Elfring
2019-07-03 9:33 ` Markus Elfring
2019-07-03 11:14 ` Mimi Zohar [this message]
2019-07-03 11:14 ` [PATCH] " Mimi Zohar
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