[PATCH net-next] net/devlink: Use strscpy() to copy strings into arrays

[PATCH net-next] net/devlink: Use strscpy() to copy strings into arrays

[david.laight.linux]

From: David Laight <david.laight.linux@gmail.com>

Replacing strcpy() with strscpy() ensures that overflow of the target
buffer cannot happen.

Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
This is one of a group of patches that remove potentially unbounded
strcpy() calls.

They are mostly replaced by strscpy() or, when strlen() has just been
called, with memcpy() (usually including the '\0').

Calls with copy string literals into arrays are left unchanged.
They are safe and easily detected as such.

The changes were made by getting the compiler to detect the calls and
then fixing the code by hand.

Note that all the changes are only compile tested.

Some Makefiles were changed to allow files to contain strcpy().
As well as 'difficult to fix' files, this included 'show' functions
as they really need to use sysfs_emit() or seq_printf().

All the patches are being sent individually to avoid very long cc lists.
Apologies for the terse commit messages and likely unexpected tags.
(There are about 100 patches in total.)

 net/devlink/param.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/devlink/param.c b/net/devlink/param.c
index cf95268da5b0..dba0a0431052 100644
--- a/net/devlink/param.c
+++ b/net/devlink/param.c
@@ -540,7 +540,7 @@ devlink_param_value_get_from_info(const struct devlink_param *param,
 		if (len == nla_len(param_data) ||
 		    len >= __DEVLINK_PARAM_MAX_STRING_VALUE)
 			return -EINVAL;
-		strcpy(value->vstr, nla_data(param_data));
+		strscpy(value->vstr, nla_data(param_data));
 		break;
 	case DEVLINK_PARAM_TYPE_BOOL:
 		if (param_data && nla_len(param_data))
-- 
2.39.5

[PATCH net-next] net/devlink: Use strscpy() to copy strings into arrays

[david.laight.linux]

From: David Laight <david.laight.linux@gmail.com>

Replacing strcpy() with strscpy() ensures that overflow of the target
buffer cannot happen.

Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
This is one of a group of patches that remove potentially unbounded
strcpy() calls.

They are mostly replaced by strscpy() or, when strlen() has just been
called, with memcpy() (usually including the '\0').

Calls with copy string literals into arrays are left unchanged.
They are safe and easily detected as such.

The changes were made by getting the compiler to detect the calls and
then fixing the code by hand.

Note that all the changes are only compile tested.

Some Makefiles were changed to allow files to contain strcpy().
As well as 'difficult to fix' files, this included 'show' functions
as they really need to use sysfs_emit() or seq_printf().

All the patches are being sent individually to avoid very long cc lists.
Apologies for the terse commit messages and likely unexpected tags.
(There are about 100 patches in total.)

 net/devlink/port.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/devlink/port.c b/net/devlink/port.c
index 485029d43428..108926d3f899 100644
--- a/net/devlink/port.c
+++ b/net/devlink/port.c
@@ -1222,7 +1222,7 @@ static void __devlink_port_type_set(struct devlink_port *devlink_port,
 			devlink_port->type_eth.ifindex = netdev->ifindex;
 			BUILD_BUG_ON(sizeof(devlink_port->type_eth.ifname) !=
 				     sizeof(netdev->name));
-			strcpy(devlink_port->type_eth.ifname, netdev->name);
+			strscpy(devlink_port->type_eth.ifname, netdev->name);
 		}
 		break;
 	case DEVLINK_PORT_TYPE_IB:
-- 
2.39.5

Re: [PATCH net-next] net/devlink: Use strscpy() to copy strings into arrays

[Paolo Abeni]

On 6/8/26 11:54 AM, david.laight.linux@gmail.com wrote:
> From: David Laight <david.laight.linux@gmail.com>
> 
> Replacing strcpy() with strscpy() ensures that overflow of the target
> buffer cannot happen.
> 
> Signed-off-by: David Laight <david.laight.linux@gmail.com>
> ---
> This is one of a group of patches that remove potentially unbounded
> strcpy() calls.
> 
> They are mostly replaced by strscpy() or, when strlen() has just been
> called, with memcpy() (usually including the '\0').
> 
> Calls with copy string literals into arrays are left unchanged.
> They are safe and easily detected as such.
> 
> The changes were made by getting the compiler to detect the calls and
> then fixing the code by hand.
> 
> Note that all the changes are only compile tested.
> 
> Some Makefiles were changed to allow files to contain strcpy().
> As well as 'difficult to fix' files, this included 'show' functions
> as they really need to use sysfs_emit() or seq_printf().
> 
> All the patches are being sent individually to avoid very long cc lists.
> Apologies for the terse commit messages and likely unexpected tags.
> (There are about 100 patches in total.)
> 
>  net/devlink/port.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/devlink/port.c b/net/devlink/port.c
> index 485029d43428..108926d3f899 100644
> --- a/net/devlink/port.c
> +++ b/net/devlink/port.c
> @@ -1222,7 +1222,7 @@ static void __devlink_port_type_set(struct devlink_port *devlink_port,
>  			devlink_port->type_eth.ifindex = netdev->ifindex;
>  			BUILD_BUG_ON(sizeof(devlink_port->type_eth.ifname) !=
>  				     sizeof(netdev->name));
> -			strcpy(devlink_port->type_eth.ifname, netdev->name);
> +			strscpy(devlink_port->type_eth.ifname, netdev->name);

Given the above BUILD_BUG, I don't see how this change can help?!?

Generally speaking, I suggest restricting this kind of tool-assisted
changes to real problems (if any).

Thanks,

Paolo

Re: [PATCH net-next] net/devlink: Use strscpy() to copy strings into arrays

[David Laight]

On Tue, 9 Jun 2026 15:39:35 +0200
Paolo Abeni <pabeni@redhat.com> wrote:

> On 6/8/26 11:54 AM, david.laight.linux@gmail.com wrote:
> > From: David Laight <david.laight.linux@gmail.com>
> > 
> > Replacing strcpy() with strscpy() ensures that overflow of the target
> > buffer cannot happen.
> > 
> > Signed-off-by: David Laight <david.laight.linux@gmail.com>
> > ---
> > This is one of a group of patches that remove potentially unbounded
> > strcpy() calls.
> > 
> > They are mostly replaced by strscpy() or, when strlen() has just been
> > called, with memcpy() (usually including the '\0').
> > 
> > Calls with copy string literals into arrays are left unchanged.
> > They are safe and easily detected as such.
> > 
> > The changes were made by getting the compiler to detect the calls and
> > then fixing the code by hand.
> > 
> > Note that all the changes are only compile tested.
> > 
> > Some Makefiles were changed to allow files to contain strcpy().
> > As well as 'difficult to fix' files, this included 'show' functions
> > as they really need to use sysfs_emit() or seq_printf().
> > 
> > All the patches are being sent individually to avoid very long cc lists.
> > Apologies for the terse commit messages and likely unexpected tags.
> > (There are about 100 patches in total.)
> > 
> >  net/devlink/port.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/net/devlink/port.c b/net/devlink/port.c
> > index 485029d43428..108926d3f899 100644
> > --- a/net/devlink/port.c
> > +++ b/net/devlink/port.c
> > @@ -1222,7 +1222,7 @@ static void __devlink_port_type_set(struct devlink_port *devlink_port,
> >  			devlink_port->type_eth.ifindex = netdev->ifindex;
> >  			BUILD_BUG_ON(sizeof(devlink_port->type_eth.ifname) !=
> >  				     sizeof(netdev->name));
> > -			strcpy(devlink_port->type_eth.ifname, netdev->name);
> > +			strscpy(devlink_port->type_eth.ifname, netdev->name);  
> 
> Given the above BUILD_BUG, I don't see how this change can help?!?
> 
> Generally speaking, I suggest restricting this kind of tool-assisted
> changes to real problems (if any).

My aim is to get to the point where the calling strcpy() is invalid
unless it is used to copy a string literal into an array.
If/when all the .c files are changed the .h file change can be committed
to stop any new potential unbounded copies being added.

I do want to look at the 'fortify' version of strspcy().
The current version can call strnlen() and then real_strscpy(), so
ends up doing the length scan twice.
(Never mind how much gets inlined.)
strscpy() between arrays could be implemented as a memcpy() of the
shorter length and an explicit zero of the final byte.

With the BUILD_BUG_ON() (which I didn't notice) the above could
be e memcpy().

-- David

> 
> Thanks,
> 
> Paolo
>