mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-24 03:24:55 +08:00
1cfd895643
In cm_write(), if the 'buf' is allocated memory but not fully consumed,
it is possible to reallocate the buffer without freeing it by passing
'*ppos' as 0 on a subsequent call.
Add an explicit kfree() before kzalloc() to prevent the possible memory
leak.
Fixes: 526b4af47f ("ACPI: Split out custom_method functionality into an own driver")
Signed-off-by: Mark Langsdorf <mlangsdo@redhat.com>
Cc: 5.4+ <stable@vger.kernel.org> # 5.4+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
104 lines
2.1 KiB
C
104 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* custom_method.c - debugfs interface for customizing ACPI control method
|
|
*/
|
|
|
|
#include <linux/init.h>
|
|
#include <linux/module.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/debugfs.h>
|
|
#include <linux/acpi.h>
|
|
#include <linux/security.h>
|
|
|
|
#include "internal.h"
|
|
|
|
MODULE_LICENSE("GPL");
|
|
|
|
static struct dentry *cm_dentry;
|
|
|
|
/* /sys/kernel/debug/acpi/custom_method */
|
|
|
|
static ssize_t cm_write(struct file *file, const char __user *user_buf,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
static char *buf;
|
|
static u32 max_size;
|
|
static u32 uncopied_bytes;
|
|
|
|
struct acpi_table_header table;
|
|
acpi_status status;
|
|
int ret;
|
|
|
|
ret = security_locked_down(LOCKDOWN_ACPI_TABLES);
|
|
if (ret)
|
|
return ret;
|
|
|
|
if (!(*ppos)) {
|
|
/* parse the table header to get the table length */
|
|
if (count <= sizeof(struct acpi_table_header))
|
|
return -EINVAL;
|
|
if (copy_from_user(&table, user_buf,
|
|
sizeof(struct acpi_table_header)))
|
|
return -EFAULT;
|
|
uncopied_bytes = max_size = table.length;
|
|
/* make sure the buf is not allocated */
|
|
kfree(buf);
|
|
buf = kzalloc(max_size, GFP_KERNEL);
|
|
if (!buf)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
if (buf == NULL)
|
|
return -EINVAL;
|
|
|
|
if ((*ppos > max_size) ||
|
|
(*ppos + count > max_size) ||
|
|
(*ppos + count < count) ||
|
|
(count > uncopied_bytes)) {
|
|
kfree(buf);
|
|
buf = NULL;
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (copy_from_user(buf + (*ppos), user_buf, count)) {
|
|
kfree(buf);
|
|
buf = NULL;
|
|
return -EFAULT;
|
|
}
|
|
|
|
uncopied_bytes -= count;
|
|
*ppos += count;
|
|
|
|
if (!uncopied_bytes) {
|
|
status = acpi_install_method(buf);
|
|
kfree(buf);
|
|
buf = NULL;
|
|
if (ACPI_FAILURE(status))
|
|
return -EINVAL;
|
|
add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE);
|
|
}
|
|
|
|
return count;
|
|
}
|
|
|
|
static const struct file_operations cm_fops = {
|
|
.write = cm_write,
|
|
.llseek = default_llseek,
|
|
};
|
|
|
|
static int __init acpi_custom_method_init(void)
|
|
{
|
|
cm_dentry = debugfs_create_file("custom_method", S_IWUSR,
|
|
acpi_debugfs_dir, NULL, &cm_fops);
|
|
return 0;
|
|
}
|
|
|
|
static void __exit acpi_custom_method_exit(void)
|
|
{
|
|
debugfs_remove(cm_dentry);
|
|
}
|
|
|
|
module_init(acpi_custom_method_init);
|
|
module_exit(acpi_custom_method_exit);
|