[PATCH] net: caif: use strlcpy() instead of strncpy()

[PATCH] net: caif: use strlcpy() instead of strncpy()

[Xiongfeng Wang]

From: Xiongfeng Wang <xiongfeng.wang@linaro.org>

gcc-8 reports

net/caif/caif_dev.c: In function 'caif_enroll_dev':
./include/linux/string.h:245:9: warning: '__builtin_strncpy' output may
be truncated copying 15 bytes from a string of length 15
[-Wstringop-truncation]

net/caif/cfctrl.c: In function 'cfctrl_linkup_request':
./include/linux/string.h:245:9: warning: '__builtin_strncpy' output may
be truncated copying 15 bytes from a string of length 15
[-Wstringop-truncation]

net/caif/cfcnfg.c: In function 'caif_connect_client':
./include/linux/string.h:245:9: warning: '__builtin_strncpy' output may
be truncated copying 15 bytes from a string of length 15
[-Wstringop-truncation]

The compiler require that the input param 'len' of strncpy() should be
greater than the length of the src string, so that '\0' is copied as
well. We can just use strlcpy() to avoid this warning.

Signed-off-by: Xiongfeng Wang <xiongfeng.wang@linaro.org>
---
 net/caif/caif_dev.c |  5 ++---
 net/caif/cfcnfg.c   | 10 ++++------
 net/caif/cfctrl.c   |  4 ++--
 3 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/net/caif/caif_dev.c b/net/caif/caif_dev.c
index 2d38b6e..e0adcd1 100644
--- a/net/caif/caif_dev.c
+++ b/net/caif/caif_dev.c
@@ -334,9 +334,8 @@ void caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
 	mutex_lock(&caifdevs->lock);
 	list_add_rcu(&caifd->list, &caifdevs->list);
 
-	strncpy(caifd->layer.name, dev->name,
-		sizeof(caifd->layer.name) - 1);
-	caifd->layer.name[sizeof(caifd->layer.name) - 1] = 0;
+	strlcpy(caifd->layer.name, dev->name,
+		sizeof(caifd->layer.name));
 	caifd->layer.transmit = transmit;
 	cfcnfg_add_phy_layer(cfg,
 				dev,
diff --git a/net/caif/cfcnfg.c b/net/caif/cfcnfg.c
index 273cb07..8f00bea 100644
--- a/net/caif/cfcnfg.c
+++ b/net/caif/cfcnfg.c
@@ -268,17 +268,15 @@ static int caif_connect_req_to_link_param(struct cfcnfg *cnfg,
 	case CAIFPROTO_RFM:
 		l->linktype = CFCTRL_SRV_RFM;
 		l->u.datagram.connid = s->sockaddr.u.rfm.connection_id;
-		strncpy(l->u.rfm.volume, s->sockaddr.u.rfm.volume,
-			sizeof(l->u.rfm.volume)-1);
-		l->u.rfm.volume[sizeof(l->u.rfm.volume)-1] = 0;
+		strlcpy(l->u.rfm.volume, s->sockaddr.u.rfm.volume,
+			sizeof(l->u.rfm.volume));
 		break;
 	case CAIFPROTO_UTIL:
 		l->linktype = CFCTRL_SRV_UTIL;
 		l->endpoint = 0x00;
 		l->chtype = 0x00;
-		strncpy(l->u.utility.name, s->sockaddr.u.util.service,
-			sizeof(l->u.utility.name)-1);
-		l->u.utility.name[sizeof(l->u.utility.name)-1] = 0;
+		strlcpy(l->u.utility.name, s->sockaddr.u.util.service,
+			sizeof(l->u.utility.name));
 		caif_assert(sizeof(l->u.utility.name) > 10);
 		l->u.utility.paramlen = s->param.size;
 		if (l->u.utility.paramlen > sizeof(l->u.utility.params))
diff --git a/net/caif/cfctrl.c b/net/caif/cfctrl.c
index f5afda1..655ed70 100644
--- a/net/caif/cfctrl.c
+++ b/net/caif/cfctrl.c
@@ -258,8 +258,8 @@ int cfctrl_linkup_request(struct cflayer *layer,
 		tmp16 = cpu_to_le16(param->u.utility.fifosize_bufs);
 		cfpkt_add_body(pkt, &tmp16, 2);
 		memset(utility_name, 0, sizeof(utility_name));
-		strncpy(utility_name, param->u.utility.name,
-			UTILITY_NAME_LENGTH - 1);
+		strlcpy(utility_name, param->u.utility.name,
+			UTILITY_NAME_LENGTH);
 		cfpkt_add_body(pkt, utility_name, UTILITY_NAME_LENGTH);
 		tmp8 = param->u.utility.paramlen;
 		cfpkt_add_body(pkt, &tmp8, 1);
-- 
1.8.3.1

Re: [PATCH] net: caif: use strlcpy() instead of strncpy()

[David Miller]

From: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Date: Mon, 8 Jan 2018 19:43:00 +0800

> From: Xiongfeng Wang <xiongfeng.wang@linaro.org>
> 
> gcc-8 reports
> 
> net/caif/caif_dev.c: In function 'caif_enroll_dev':
> ./include/linux/string.h:245:9: warning: '__builtin_strncpy' output may
> be truncated copying 15 bytes from a string of length 15
> [-Wstringop-truncation]
> 
> net/caif/cfctrl.c: In function 'cfctrl_linkup_request':
> ./include/linux/string.h:245:9: warning: '__builtin_strncpy' output may
> be truncated copying 15 bytes from a string of length 15
> [-Wstringop-truncation]
> 
> net/caif/cfcnfg.c: In function 'caif_connect_client':
> ./include/linux/string.h:245:9: warning: '__builtin_strncpy' output may
> be truncated copying 15 bytes from a string of length 15
> [-Wstringop-truncation]
> 
> The compiler require that the input param 'len' of strncpy() should be
> greater than the length of the src string, so that '\0' is copied as
> well. We can just use strlcpy() to avoid this warning.
> 
> Signed-off-by: Xiongfeng Wang <xiongfeng.wang@linaro.org>

Applied, thank you.