[PATCH AUTOSEL 4.14 36/87] scsi: ibmvscsi: Improve strings handling

From: Sasha Levin
Date: Sun Sep 16 2018 - 23:04:24 EST

From: Breno Leitao <leitao@xxxxxxxxxx>

[ Upstream commit 1262dc09dc9ae7bf4ad00b6a2c5ed6a6936bcd10 ]

Currently an open firmware property is copied into partition_name variable
without keeping a room for \0.

Later one, this variable (partition_name), which is 97 bytes long, is
strncpyed into ibmvcsci_host_data->madapter_info->partition_name, which is
96 bytes long, possibly truncating it 'again' and removing the \0.

This patch simply decreases the partition name to 96 and just copy using
strlcpy() which guarantees that the string is \0 terminated. I think there
is no issue if this there is a truncation in this very first copy, i.e,
when the open firmware property is read and copied into the driver for the
very first time;

This issue also causes the following warning on GCC 8:

drivers/scsi/ibmvscsi/ibmvscsi.c:281:2: warning: strncpy output may be truncated copying 96 bytes from a string of length 96 [-Wstringop-truncation]
inlined from ibmvscsi_probe at drivers/scsi/ibmvscsi/ibmvscsi.c:2221:7:
drivers/scsi/ibmvscsi/ibmvscsi.c:265:3: warning: strncpy specified bound 97 equals destination size [-Wstringop-truncation]

CC: Bart Van Assche <bart.vanassche@xxxxxxx>
CC: Tyrel Datwyler <tyreld@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>
Acked-by: Tyrel Datwyler <tyreld@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
drivers/scsi/ibmvscsi/ibmvscsi.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index 7d156b161482..53eb27731373 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -93,7 +93,7 @@ static int max_requests = IBMVSCSI_MAX_REQUESTS_DEFAULT;
static int max_events = IBMVSCSI_MAX_REQUESTS_DEFAULT + 2;
static int fast_fail = 1;
static int client_reserve = 1;
-static char partition_name[97] = "UNKNOWN";
+static char partition_name[96] = "UNKNOWN";
static unsigned int partition_number = -1;
static LIST_HEAD(ibmvscsi_head);

@@ -262,7 +262,7 @@ static void gather_partition_info(void)

ppartition_name = of_get_property(of_root, "ibm,partition-name", NULL);
if (ppartition_name)
- strncpy(partition_name, ppartition_name,
+ strlcpy(partition_name, ppartition_name,
p_number_ptr = of_get_property(of_root, "ibm,partition-no", NULL);
if (p_number_ptr)