linux-kernel - [PATCH] firmware: qemu_fw_cfg: constify 'struct bin

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Message-Id: <20250114-sysfs-const-bin_attr-qemu_fw_cfg-v1-1-76f525a3ee72@weissschuh.net>
Date: Tue, 14 Jan 2025 22:50:20 +0100
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Gabriel Somlo <somlo@....edu>, "Michael S. Tsirkin" <mst@...hat.com>
Cc: qemu-devel@...gnu.org, linux-kernel@...r.kernel.org, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH] 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 <linux@...ssschuh.net>
---
 drivers/firmware/qemu_fw_cfg.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
index d58da3e4500a5e230b7da9a75e4d70df7c38c542..2615fb780e3c4500db36d4746880455f05479f1f 100644
--- a/drivers/firmware/qemu_fw_cfg.c
+++ b/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,
 };

 /*

---
base-commit: 7f5b6a8ec18e3add4c74682f60b90c31bdf849f2
change-id: 20250114-sysfs-const-bin_attr-qemu_fw_cfg-fa4a95934904

Best regards,
-- 
Thomas Weißschuh <linux@...ssschuh.net>