[PATCH net-next] net/9p: Replace strlen() strcpy() pair with strscpy()

[PATCH net-next] net/9p: Replace strlen() strcpy() pair with strscpy()

[david.laight.linux]

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

Use the result of strscpy() for the overflow check.

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/9p/trans_fd.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index dbad3213ba84..eb685b52aeb2 100644
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -940,14 +940,12 @@ p9_fd_create_unix(struct p9_client *client, struct fs_context *fc)
 	if (!addr || !strlen(addr))
 		return -EINVAL;
 
-	if (strlen(addr) >= UNIX_PATH_MAX) {
+	sun_server.sun_family = PF_UNIX;
+	if (strscpy(sun_server.sun_path, addr) < 0) {
 		pr_err("%s (%d): address too long: %s\n",
 		       __func__, task_pid_nr(current), addr);
 		return -ENAMETOOLONG;
 	}
-
-	sun_server.sun_family = PF_UNIX;
-	strcpy(sun_server.sun_path, addr);
 	err = __sock_create(current->nsproxy->net_ns, PF_UNIX,
 			    SOCK_STREAM, 0, &csocket, 1);
 	if (err < 0) {
-- 
2.39.5

Re: [PATCH net-next] net/9p: Replace strlen() strcpy() pair with strscpy()

[Dominique Martinet]

david.laight.linux@gmail.com wrote on Sat, Jun 06, 2026 at 09:27:42PM +0100:
> From: David Laight <david.laight.linux@gmail.com>
> 
> Use the result of strscpy() for the overflow check.
> 
> Signed-off-by: David Laight <david.laight.linux@gmail.com>

Thanks, picked up in 9p tree

-- 
Dominique