[PATCH] ipv6: replace sprintf() with no format specifiers with strscpy()

[PATCH] ipv6: replace sprintf() with no format specifiers with strscpy()

[Lalit Shankar Chowdhury]

Multiple instances of sprintf() have no format specifiers. Replace
them with strscpy().

Signed-off-by: Lalit Shankar Chowdhury <lalitshankarch@gmail.com>
---
 net/ipv6/ip6_tunnel.c | 2 +-
 net/ipv6/ip6_vti.c    | 2 +-
 net/ipv6/ip6mr.c      | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index d5ff50a2ac01..ef3a6d931c9e 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -294,7 +294,7 @@ static struct ip6_tnl *ip6_tnl_create(struct net *net, struct __ip6_tnl_parm *p)
 			goto failed;
 		strscpy(name, p->name, IFNAMSIZ);
 	} else {
-		sprintf(name, "ip6tnl%%d");
+		strscpy(name, "ip6tnl%d", IFNAMSIZ);
 	}
 	err = -ENOMEM;
 	dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN,
diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
index ab94b3a4ba9c..182a7949d830 100644
--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -210,7 +210,7 @@ static struct ip6_tnl *vti6_tnl_create(struct net *net, struct __ip6_tnl_parm *p
 			goto failed;
 		strscpy(name, p->name, IFNAMSIZ);
 	} else {
-		sprintf(name, "ip6_vti%%d");
+		strscpy(name, "ip6_vti%d", IFNAMSIZ);
 	}
 
 	dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN, vti6_dev_setup);
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 3f2ed9b77deb..20ac8cb87468 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -692,7 +692,7 @@ static struct net_device *ip6mr_reg_vif(struct net *net, struct mr_table *mrt)
 	char name[IFNAMSIZ];
 
 	if (mrt->id == RT6_TABLE_DFLT)
-		sprintf(name, "pim6reg");
+		strscpy(name, "pim6reg", IFNAMSIZ);
 	else
 		sprintf(name, "pim6reg%u", mrt->id);
 
-- 
2.53.0

Re: [PATCH] ipv6: replace sprintf() with no format specifiers with strscpy()

[Hangbin Liu]

Hi Lalit,
On Wed, Sep 09, 2026 at 09:05:52PM +0000, Lalit Shankar Chowdhury wrote:
> Multiple instances of sprintf() have no format specifiers. Replace
> them with strscpy().
> 
> Signed-off-by: Lalit Shankar Chowdhury <lalitshankarch@gmail.com>
> ---
>  net/ipv6/ip6_tunnel.c | 2 +-
>  net/ipv6/ip6_vti.c    | 2 +-
>  net/ipv6/ip6mr.c      | 2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
> index d5ff50a2ac01..ef3a6d931c9e 100644
> --- a/net/ipv6/ip6_tunnel.c
> +++ b/net/ipv6/ip6_tunnel.c
> @@ -294,7 +294,7 @@ static struct ip6_tnl *ip6_tnl_create(struct net *net, struct __ip6_tnl_parm *p)
>  			goto failed;
>  		strscpy(name, p->name, IFNAMSIZ);
>  	} else {
> -		sprintf(name, "ip6tnl%%d");
> +		strscpy(name, "ip6tnl%d", IFNAMSIZ);

The sprintf() is doing format expansion (%% -> %), the name will be used
in __dev_alloc_name() later. I think there is no need to change them.

Thanks
Hangbin

Re: [PATCH] ipv6: replace sprintf() with no format specifiers with strscpy()

[David Laight]

On Wed,  9 Sep 2026 21:05:52 +0000
Lalit Shankar Chowdhury <lalitshankarch@gmail.com> wrote:

> Multiple instances of sprintf() have no format specifiers. Replace
> them with strscpy().
> 
> Signed-off-by: Lalit Shankar Chowdhury <lalitshankarch@gmail.com>
> ---
>  net/ipv6/ip6_tunnel.c | 2 +-
>  net/ipv6/ip6_vti.c    | 2 +-
>  net/ipv6/ip6mr.c      | 2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
> index d5ff50a2ac01..ef3a6d931c9e 100644
> --- a/net/ipv6/ip6_tunnel.c
> +++ b/net/ipv6/ip6_tunnel.c
> @@ -294,7 +294,7 @@ static struct ip6_tnl *ip6_tnl_create(struct net *net, struct __ip6_tnl_parm *p)
>  			goto failed;
>  		strscpy(name, p->name, IFNAMSIZ);
>  	} else {
> -		sprintf(name, "ip6tnl%%d");
> +		strscpy(name, "ip6tnl%d", IFNAMSIZ);
>  	}
>  	err = -ENOMEM;
>  	dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN,

That code is silly, there is no need for the copies at all.
Something like:
	if (p->name[0] && !dev_valid_name[p->name])
		return ERR_PTR(-E2BIG);
	dev = alloc_netdev(sizeof(*t), p->name[0] ? p->name : "op6tnl%d",
			   NET_NAME_UNKNOWN, ip6_tnl_dev_setup);
	if (!dev)
		return ERR_PTR(-ENOMEM);

David

> diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
> index ab94b3a4ba9c..182a7949d830 100644
> --- a/net/ipv6/ip6_vti.c
> +++ b/net/ipv6/ip6_vti.c
> @@ -210,7 +210,7 @@ static struct ip6_tnl *vti6_tnl_create(struct net *net, struct __ip6_tnl_parm *p
>  			goto failed;
>  		strscpy(name, p->name, IFNAMSIZ);
>  	} else {
> -		sprintf(name, "ip6_vti%%d");
> +		strscpy(name, "ip6_vti%d", IFNAMSIZ);
>  	}
>  
>  	dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN, vti6_dev_setup);
> diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
> index 3f2ed9b77deb..20ac8cb87468 100644
> --- a/net/ipv6/ip6mr.c
> +++ b/net/ipv6/ip6mr.c
> @@ -692,7 +692,7 @@ static struct net_device *ip6mr_reg_vif(struct net *net, struct mr_table *mrt)
>  	char name[IFNAMSIZ];
>  
>  	if (mrt->id == RT6_TABLE_DFLT)
> -		sprintf(name, "pim6reg");
> +		strscpy(name, "pim6reg", IFNAMSIZ);
>  	else
>  		sprintf(name, "pim6reg%u", mrt->id);
>