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Mon, 15 Mar 2021 21:48:23 GMT Received: from b03ledav001.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A20936E04E; Mon, 15 Mar 2021 21:48:23 +0000 (GMT) Received: from b03ledav001.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 663DC6E04C; Mon, 15 Mar 2021 21:48:23 +0000 (GMT) Received: from vios4361.aus.stglabs.ibm.com (unknown [9.3.43.61]) by b03ledav001.gho.boulder.ibm.com (Postfix) with ESMTP; Mon, 15 Mar 2021 21:48:23 +0000 (GMT) From: Tyrel Datwyler To: bhelgaas@google.com Cc: linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Tyrel Datwyler Subject: [PATCH v2] rpadlpar: fix potential drc_name corruption in store functions Date: Mon, 15 Mar 2021 15:48:21 -0600 Message-Id: <20210315214821.452959-1-tyreld@linux.ibm.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.761 definitions=2021-03-15_12:2021-03-15,2021-03-15 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 suspectscore=0 bulkscore=0 impostorscore=0 mlxscore=0 mlxlogscore=999 phishscore=0 lowpriorityscore=0 priorityscore=1501 clxscore=1015 spamscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2103150145 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Both add_slot_store() and remove_slot_store() try to fix up the drc_name copied from the store buffer by placing a NULL terminator at nbyte + 1 or in place of a '\n' if present. However, the static buffer that we copy the drc_name data into is not zeored and can contain anything past the n-th byte. This is problematic if a '\n' byte appears in that buffer after nbytes and the string copied into the store buffer was not NULL terminated to start with as the strchr() search for a '\n' byte will mark this incorrectly as the end of the drc_name string resulting in a drc_name string that contains garbage data after the n-th byte. The following debugging shows an example of the drmgr utility writing "PHB 4543" to the add_slot sysfs attribute, but add_slot_store logging a corrupted string value. [135823.702864] drmgr: drmgr: -c phb -a -s PHB 4543 -d 1 [135823.702879] add_slot_store: drc_name = PHB 4543°|<82>!, rc = -19 Fix this by using strscpy() instead of memcpy() to ensure the string is NULL terminated when copied into the static drc_name buffer. Further, since the string is now NULL terminated the code only needs to change '\n' to '\0' when present. Signed-off-by: Tyrel Datwyler --- Changes in v2: * use strscpy instead of memcpy (suggested by mpe) drivers/pci/hotplug/rpadlpar_sysfs.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/drivers/pci/hotplug/rpadlpar_sysfs.c b/drivers/pci/hotplug/rpadlpar_sysfs.c index cdbfa5df3a51..dbfa0b55d31a 100644 --- a/drivers/pci/hotplug/rpadlpar_sysfs.c +++ b/drivers/pci/hotplug/rpadlpar_sysfs.c @@ -34,12 +34,11 @@ static ssize_t add_slot_store(struct kobject *kobj, struct kobj_attribute *attr, if (nbytes >= MAX_DRC_NAME_LEN) return 0; - memcpy(drc_name, buf, nbytes); + strscpy(drc_name, buf, nbytes + 1); end = strchr(drc_name, '\n'); - if (!end) - end = &drc_name[nbytes]; - *end = '\0'; + if (end) + *end = '\0'; rc = dlpar_add_slot(drc_name); if (rc) @@ -65,12 +64,11 @@ static ssize_t remove_slot_store(struct kobject *kobj, if (nbytes >= MAX_DRC_NAME_LEN) return 0; - memcpy(drc_name, buf, nbytes); + strscpy(drc_name, buf, nbytes + 1); end = strchr(drc_name, '\n'); - if (!end) - end = &drc_name[nbytes]; - *end = '\0'; + if (end) + *end = '\0'; rc = dlpar_remove_slot(drc_name); if (rc)