firmware: qemu_fw_cfg: constify 'struct bin_attribute'

The sysfs core now allows instances of 'struct bin_attribute' to be
moved into read-only memory. Make use of that to protect them against
accidental or malicious modifications.

Signed-off-by: Thomas Weißschuh <[email protected]>
Acked-by: Gabriel Somlo <[email protected]>
Acked-by: Michael S. Tsirkin <[email protected]>
Link: https://lore.kernel.org/r/20250114-sysfs-const-bin_attr-qemu_fw_cfg-v1-1-76f525a3ee72@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: t-8ch

drivers/firmware/qemu_fw_cfg.c

@@ -460,7 +460,7 @@ static const struct kobj_type fw_cfg_sysfs_entry_ktype = {
 
 /* raw-read method and attribute */
 static ssize_t fw_cfg_sysfs_read_raw(struct file *filp, struct kobject *kobj,
-				     struct bin_attribute *bin_attr,
+				     const struct bin_attribute *bin_attr,
 				     char *buf, loff_t pos, size_t count)
 {
 	struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
@@ -474,9 +474,9 @@ static ssize_t fw_cfg_sysfs_read_raw(struct file *filp, struct kobject *kobj,
 	return fw_cfg_read_blob(entry->select, buf, pos, count);
 }
 
-static struct bin_attribute fw_cfg_sysfs_attr_raw = {
+static const struct bin_attribute fw_cfg_sysfs_attr_raw = {
 	.attr = { .name = "raw", .mode = S_IRUSR },
-	.read = fw_cfg_sysfs_read_raw,
+	.read_new = fw_cfg_sysfs_read_raw,
 };
 
 /*