s390/iucv: Fix vargs handling in iucv_alloc_device()

JIRA: https://issues.redhat.com/browse/RHEL-50786
Upstream status: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Tested: by IBM
Build-Info: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=65307356
Conflicts: None

commit 0124fb0

    iucv_alloc_device() gets a format string and a varying number of
    arguments. This is incorrectly forwarded by calling dev_set_name() with
    the format string and a va_list, while dev_set_name() expects also a
    varying number of arguments.

    Symptoms:
    Corrupted iucv device names, which can result in log messages like:
    sysfs: cannot create duplicate filename '/devices/iucv/hvc_iucv1827699952'

    Fixes: 4452e8e ("s390/iucv: Provide iucv_alloc_device() / iucv_release_device()")
    Link: https://bugzilla.suse.com/show_bug.cgi?id=1228425
    Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
    Reviewed-by: Thorsten Winkler <twinkler@linux.ibm.com>
    Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
    Link: https://patch.msgid.link/20240821091337.3627068-1-wintera@linux.ibm.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Mete Durlu <mdurlu@redhat.com>

Author: Mete Durlu

net/iucv/iucv.c

@@ -87,13 +87,15 @@ struct device *iucv_alloc_device(const struct attribute_group **attrs,
 {
 	struct device *dev;
 	va_list vargs;
+	char buf[20];
 	int rc;
 
 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 	if (!dev)
 		goto out_error;
 	va_start(vargs, fmt);
-	rc = dev_set_name(dev, fmt, vargs);
+	vsnprintf(buf, sizeof(buf), fmt, vargs);
+	rc = dev_set_name(dev, "%s", buf);
 	va_end(vargs);
 	if (rc)
 		goto out_error;