From: Dan Carpenter <dan.carpenter@oracle.com>
To: jwi@linux.ibm.com
Cc: linux-s390@vger.kernel.org, Kees Cook <keescook@chromium.org>
Subject: [bug report] s390/qeth: streamline SNMP cmd code
Date: Tue, 20 Aug 2019 14:05:04 +0300 [thread overview]
Message-ID: <20190820110504.GA1847@mwanda> (raw)
[ Kees, could we make copy_from_user() just fail if size is more than
INT_MAX? ]
Hello Julian Wiedmann,
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 reply other threads:[~2019-08-20 11:05 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-20 11:05 Dan Carpenter [this message]
2019-08-20 13:56 ` [bug report] s390/qeth: streamline SNMP cmd code Julian Wiedmann
2019-08-20 16:43 ` Kees Cook
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