mirror of
https://github.com/torvalds/linux.git
synced 2024-11-28 07:01:32 +00:00
f37ccf8fce
clang's Control Flow Integrity requires that every indirect call has a
valid target, which is based on the type of the function pointer. The
*_show() functions in this file are written as if they will be called
from dev_attr_show(); however, they will be called from
sysfs_kf_seq_show() because the files were created by
sysfs_create_group() and the sysfs ops are based on kobj_sysfs_ops
because of kobject_add_and_create(). Because the *_show() functions do
not match the type of the show() member in struct kobj_attribute, there
is a CFI violation.
$ cat /sys/firmware/acpi/bgrt/{status,type,version,{x,y}offset}}
1
0
1
522
307
$ dmesg | grep "CFI failure"
[ 267.761825] CFI failure (target: type_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8):
[ 267.762246] CFI failure (target: xoffset_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8):
[ 267.762584] CFI failure (target: status_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8):
[ 267.762973] CFI failure (target: yoffset_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8):
[ 267.763330] CFI failure (target: version_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8):
Convert these functions to the type of the show() member in struct
kobj_attribute so that there is no more CFI violation. Because these
functions are all so similar, combine them into a macro.
Fixes: d1ff4b1cdb ("ACPI: Add support for exposing BGRT data")
Link: https://github.com/ClangBuiltLinux/linux/issues/1406
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
102 lines
2.3 KiB
C
102 lines
2.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* BGRT boot graphic support
|
|
* Authors: Matthew Garrett, Josh Triplett <josh@joshtriplett.org>
|
|
* Copyright 2012 Red Hat, Inc <mjg@redhat.com>
|
|
* Copyright 2012 Intel Corporation
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/init.h>
|
|
#include <linux/device.h>
|
|
#include <linux/sysfs.h>
|
|
#include <linux/efi-bgrt.h>
|
|
|
|
static void *bgrt_image;
|
|
static struct kobject *bgrt_kobj;
|
|
|
|
#define BGRT_SHOW(_name, _member) \
|
|
static ssize_t _name##_show(struct kobject *kobj, \
|
|
struct kobj_attribute *attr, char *buf) \
|
|
{ \
|
|
return snprintf(buf, PAGE_SIZE, "%d\n", bgrt_tab._member); \
|
|
} \
|
|
struct kobj_attribute bgrt_attr_##_name = __ATTR_RO(_name)
|
|
|
|
BGRT_SHOW(version, version);
|
|
BGRT_SHOW(status, status);
|
|
BGRT_SHOW(type, image_type);
|
|
BGRT_SHOW(xoffset, image_offset_x);
|
|
BGRT_SHOW(yoffset, image_offset_y);
|
|
|
|
static ssize_t image_read(struct file *file, struct kobject *kobj,
|
|
struct bin_attribute *attr, char *buf, loff_t off, size_t count)
|
|
{
|
|
memcpy(buf, attr->private + off, count);
|
|
return count;
|
|
}
|
|
|
|
static BIN_ATTR_RO(image, 0); /* size gets filled in later */
|
|
|
|
static struct attribute *bgrt_attributes[] = {
|
|
&bgrt_attr_version.attr,
|
|
&bgrt_attr_status.attr,
|
|
&bgrt_attr_type.attr,
|
|
&bgrt_attr_xoffset.attr,
|
|
&bgrt_attr_yoffset.attr,
|
|
NULL,
|
|
};
|
|
|
|
static struct bin_attribute *bgrt_bin_attributes[] = {
|
|
&bin_attr_image,
|
|
NULL,
|
|
};
|
|
|
|
static const struct attribute_group bgrt_attribute_group = {
|
|
.attrs = bgrt_attributes,
|
|
.bin_attrs = bgrt_bin_attributes,
|
|
};
|
|
|
|
int __init acpi_parse_bgrt(struct acpi_table_header *table)
|
|
{
|
|
efi_bgrt_init(table);
|
|
return 0;
|
|
}
|
|
|
|
static int __init bgrt_init(void)
|
|
{
|
|
int ret;
|
|
|
|
if (!bgrt_tab.image_address)
|
|
return -ENODEV;
|
|
|
|
bgrt_image = memremap(bgrt_tab.image_address, bgrt_image_size,
|
|
MEMREMAP_WB);
|
|
if (!bgrt_image) {
|
|
pr_notice("Ignoring BGRT: failed to map image memory\n");
|
|
return -ENOMEM;
|
|
}
|
|
|
|
bin_attr_image.private = bgrt_image;
|
|
bin_attr_image.size = bgrt_image_size;
|
|
|
|
bgrt_kobj = kobject_create_and_add("bgrt", acpi_kobj);
|
|
if (!bgrt_kobj) {
|
|
ret = -EINVAL;
|
|
goto out_memmap;
|
|
}
|
|
|
|
ret = sysfs_create_group(bgrt_kobj, &bgrt_attribute_group);
|
|
if (ret)
|
|
goto out_kobject;
|
|
|
|
return 0;
|
|
|
|
out_kobject:
|
|
kobject_put(bgrt_kobj);
|
|
out_memmap:
|
|
memunmap(bgrt_image);
|
|
return ret;
|
|
}
|
|
device_initcall(bgrt_init);
|