b69edab47f
Under CONFIG_FORTIFY_SOURCE, memcpy() will check the size of destination
and source buffers. Defining kernel_headers_data as "char" would trip
this check. Since these addresses are treated as byte arrays, define
them as arrays (as done everywhere else).
This was seen with:
$ cat /sys/kernel/kheaders.tar.xz >> /dev/null
detected buffer overflow in memcpy
kernel BUG at lib/string_helpers.c:1027!
...
RIP: 0010:fortify_panic+0xf/0x20
[...]
Call Trace:
<TASK>
ikheaders_read+0x45/0x50 [kheaders]
kernfs_fop_read_iter+0x1a4/0x2f0
...
Reported-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/bpf/20230302112130.6e402a98@kernel.org/
Acked-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Tested-by: Jakub Kicinski <kuba@kernel.org>
Fixes: 43d8ce9d65 ("Provide in-kernel headers to make extending kernel easier")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230302224946.never.243-kees@kernel.org
67 lines
1.6 KiB
C
67 lines
1.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Provide kernel headers useful to build tracing programs
|
|
* such as for running eBPF tracing tools.
|
|
*
|
|
* (Borrowed code from kernel/configs.c)
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/kobject.h>
|
|
#include <linux/init.h>
|
|
|
|
/*
|
|
* Define kernel_headers_data and kernel_headers_data_end, within which the
|
|
* compressed kernel headers are stored. The file is first compressed with xz.
|
|
*/
|
|
|
|
asm (
|
|
" .pushsection .rodata, \"a\" \n"
|
|
" .global kernel_headers_data \n"
|
|
"kernel_headers_data: \n"
|
|
" .incbin \"kernel/kheaders_data.tar.xz\" \n"
|
|
" .global kernel_headers_data_end \n"
|
|
"kernel_headers_data_end: \n"
|
|
" .popsection \n"
|
|
);
|
|
|
|
extern char kernel_headers_data[];
|
|
extern char kernel_headers_data_end[];
|
|
|
|
static ssize_t
|
|
ikheaders_read(struct file *file, struct kobject *kobj,
|
|
struct bin_attribute *bin_attr,
|
|
char *buf, loff_t off, size_t len)
|
|
{
|
|
memcpy(buf, &kernel_headers_data[off], len);
|
|
return len;
|
|
}
|
|
|
|
static struct bin_attribute kheaders_attr __ro_after_init = {
|
|
.attr = {
|
|
.name = "kheaders.tar.xz",
|
|
.mode = 0444,
|
|
},
|
|
.read = &ikheaders_read,
|
|
};
|
|
|
|
static int __init ikheaders_init(void)
|
|
{
|
|
kheaders_attr.size = (kernel_headers_data_end -
|
|
kernel_headers_data);
|
|
return sysfs_create_bin_file(kernel_kobj, &kheaders_attr);
|
|
}
|
|
|
|
static void __exit ikheaders_cleanup(void)
|
|
{
|
|
sysfs_remove_bin_file(kernel_kobj, &kheaders_attr);
|
|
}
|
|
|
|
module_init(ikheaders_init);
|
|
module_exit(ikheaders_cleanup);
|
|
|
|
MODULE_LICENSE("GPL v2");
|
|
MODULE_AUTHOR("Joel Fernandes");
|
|
MODULE_DESCRIPTION("Echo the kernel header artifacts used to build the kernel");
|