From: Julian Wiedmann <jwi@linux.ibm.com>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: linux-s390@vger.kernel.org, Kees Cook <keescook@chromium.org>,
Ursula Braun <ubraun@linux.ibm.com>
Subject: Re: [bug report] s390/qeth: streamline SNMP cmd code
Date: Tue, 20 Aug 2019 15:56:47 +0200 [thread overview]
Message-ID: <95addda5-aa7e-32f3-0665-42fb7847788a@linux.ibm.com> (raw)
In-Reply-To: <20190820110504.GA1847@mwanda>
On 20.08.19 13:05, Dan Carpenter wrote:
> [ Kees, could we make copy_from_user() just fail if size is more than
> INT_MAX? ]
>
> Hello Julian Wiedmann,
>
Heya Dan - thanks! Agreed, that looks wrong. I'll put together a fix...
> The patch d4c08afafa04: "s390/qeth: streamline SNMP cmd code" from
> Jun 27, 2019, leads to the following static checker warning:
>
> drivers/s390/net/qeth_core_main.c:4381 qeth_snmp_command()
> error: check that 'req_len' is capped
>
> drivers/s390/net/qeth_core_main.c
> 4355 static int qeth_snmp_command(struct qeth_card *card, char __user *udata)
> 4356 {
> 4357 struct qeth_snmp_ureq __user *ureq;
> 4358 struct qeth_cmd_buffer *iob;
> 4359 unsigned int req_len;
> 4360 struct qeth_arp_query_info qinfo = {0, };
> 4361 int rc = 0;
> 4362
> 4363 QETH_CARD_TEXT(card, 3, "snmpcmd");
> 4364
> 4365 if (IS_VM_NIC(card))
> 4366 return -EOPNOTSUPP;
> 4367
> 4368 if ((!qeth_adp_supported(card, IPA_SETADP_SET_SNMP_CONTROL)) &&
> 4369 IS_LAYER3(card))
> 4370 return -EOPNOTSUPP;
> 4371
> 4372 ureq = (struct qeth_snmp_ureq __user *) udata;
> 4373 if (get_user(qinfo.udata_len, &ureq->hdr.data_len) ||
> 4374 get_user(req_len, &ureq->hdr.req_len))
> 4375 return -EFAULT;
> 4376
> 4377 iob = qeth_get_adapter_cmd(card, IPA_SETADP_SET_SNMP_CONTROL, req_len);
>
> The problem is that qeth_get_adapter_cmd() doesn't guard against integer
> overflows if reg_len is >= UINT_MAX - offsetof(struct qeth_ipacmd_setadpparms,
> data)).
>
> 4378 if (!iob)
> 4379 return -ENOMEM;
> 4380
> 4381 if (copy_from_user(&__ipa_cmd(iob)->data.setadapterparms.data.snmp,
> 4382 &ureq->cmd, req_len)) {
>
> So then this copy_from_user() could overflow. The original code had a
> similar problem but it only affect 32 bit systems. I'm not sure what is
> a good upper bound for req_len.
>
> 4383 qeth_put_cmd(iob);
> 4384 return -EFAULT;
> 4385 }
> 4386
> 4387 qinfo.udata = kzalloc(qinfo.udata_len, GFP_KERNEL);
>
> regards,
> dan carpenter
>
next prev parent reply other threads:[~2019-08-20 13:57 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-20 11:05 [bug report] s390/qeth: streamline SNMP cmd code Dan Carpenter
2019-08-20 13:56 ` Julian Wiedmann [this message]
2019-08-20 16:43 ` Kees Cook
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=95addda5-aa7e-32f3-0665-42fb7847788a@linux.ibm.com \
--to=jwi@linux.ibm.com \
--cc=dan.carpenter@oracle.com \
--cc=keescook@chromium.org \
--cc=linux-s390@vger.kernel.org \
--cc=ubraun@linux.ibm.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