can't load kernel module in kernel 5.15.x

[hidekuno]

Version

Microsoft Windows [Version 10.0.22621.1105]

WSL Version

• WSL 2
• WSL 1

Kernel Version

5.15.79.1

Distro Version

Ubuntu 20.04

Other Software

No response

Repro Steps

1. install WSL kernel source.

cd /usr/src
sudo git clone https://github.com/microsoft/WSL2-Linux-Kernel.git
cd WSL2-Linux-Kernel
sudo git checkout linux-msft-wsl-5.15.y
sudo bash -c "cat /proc/config.gz  | gzip -dc > /usr/src/WSL2-Linux-Kernel/.config"
sudo make modules_prepare
sudo make scripts

2. prepare kernel module sample program.

cat <<EOF>hello.c
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("John Doe");
MODULE_DESCRIPTION("A sample Linux kernel module");
MODULE_VERSION("0.1");

static int __init hello_init(void)
{
    printk(KERN_INFO "Hello, kernel\n");
    return 0;
}
static void __exit hello_exit(void)
{
    printk(KERN_INFO "Goodbye, kernel\n");
}
module_init(hello_init);
module_exit(hello_exit);
EOF

3. build sample kernel module.

make -C /usr/src/WSL2-Linux-Kernel M=`pwd` modules

4. load sample kernel module.

sudo insmod hello.ko

Expected Behavior

The result of the command "sudo insmod hello.ko; dmesg |tail -1" is "Hello, kernel"

Actual Behavior

• The result of "sudo insmod hello.ko" was as below.

insmod: ERROR: could not insert module hello.ko: Invalid module format

• The result of the command "dmesg |tail -1" was as below.

[ 5551.749096] module: x86/modules: Skipping invalid relocation target, existing value is nonzero for type 1, loc 00000000b87c689f, val ffffffffc000c000

Diagnostic Logs

No response

[0xbadfca11]

Your build environment seems corrupted.

typed command

sudo apt update
sudo apt install -y build-essential flex bison dwarves libssl-dev libelf-dev bc
git clone https://github.com/microsoft/WSL2-Linux-Kernel.git --branch=linux-msft-wsl-5.15.y --depth=1
cd WSL2-Linux-Kernel/
zcat /proc/config.gz > .config
make olddefconfig modules_prepare scripts
cd
mkdir a
cd a
cat <<EOF>hello.c
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("John Doe");
MODULE_DESCRIPTION("A sample Linux kernel module");
MODULE_VERSION("0.1");

static int __init hello_init(void)
{
    printk(KERN_INFO "Hello, kernel\n");
    return 0;
}
static void __exit hello_exit(void)
{
    printk(KERN_INFO "Goodbye, kernel\n");
}
module_init(hello_init);
module_exit(hello_exit);
EOF
echo 'obj-m := hello.o' > Makefile
make -C ~/WSL2-Linux-Kernel M=`pwd` modules
sudo insmod hello.ko

[hidekuno]

I tried the steps you performed, but the result was NG.

This may be caused by a mismatch between the installed gcc version and that built the kernel.

$ zcat  /proc/config.gz |grep GCC
CONFIG_CC_VERSION_TEXT="x86_64-msft-linux-gcc (GCC) 9.3.0"
CONFIG_CC_IS_GCC=y
CONFIG_GCC_VERSION=90300
CONFIG_HAVE_GCC_PLUGINS=y
# CONFIG_GCC_PLUGINS is not set
$ gcc --version |head -1
gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0
$

Thank you.

[elsaco]

@hidekuno look at the compiler version in WSL2-Linux-Kernel\.config. Even if id doesn't match the one in /proc/config.gz it builds a loadable module.

elsaco@RIPPER:~/bar$ zcat /proc/config.gz | grep GCC_VERSION
CONFIG_GCC_VERSION=90300

elsaco@RIPPER:~/WSL2-Linux-Kernel$ grep GCC_VERSION .config
CONFIG_GCC_VERSION=110300

So the kernel source was prepared with GCC 11.3.0 and here's output of module loading/unloading:

[10533.701247] hello: no symbol version for module_layout
[10533.701252] hello: loading out-of-tree module taints kernel.
[10533.701565] Hello, kernel
[10540.535217] Goodbye, kernel

[hidekuno]

look at the compiler version in WSL2-Linux-Kernel.config. Even if id doesn't match the one in /proc/config.gz it builds a loadable module.
(snip)
So the kernel source was prepared with GCC 11.3.0 and here's output of module loading/unloading:

OK, I understanded it.
I will look into other causes
Thank you.

[qawsed90]

Build with CBL-Mariner2.0. see #10450 (comment)

[hidekuno]

thank you.
I installed dwarves and it solved the problem.

sudo apt-get install dwarves

[Henry-Xing]

Hi, I met the same problem, how did you solve this later?

[Henry-Xing]

I found this could be solved with reinstall WSL2, there might be some problem of version mismatch.

[hidekuno]

Installing dwarves solved the problem.
Please refer to the following URL for the cause of my failure.

#9608 (comment)

[TranDuyMy2407]

i followed the step but i can not load my kernel module. Anyone have solution for this issue ? This is the logs

my@LPPMYTD6:~/day12/day12/2/virt_to_phys$ make
make -C /usr/src/WSL2-Linux-Kernel M=/home/my/day12/day12/2/virt_to_phys modules
make[1]: Entering directory '/usr/src/WSL2-Linux-Kernel'
  CC [M]  /home/my/day12/day12/2/virt_to_phys/hello.o
  MODPOST /home/my/day12/day12/2/virt_to_phys/Module.symvers
  CC [M]  /home/my/day12/day12/2/virt_to_phys/hello.mod.o
  LD [M]  /home/my/day12/day12/2/virt_to_phys/hello.ko
  BTF [M] /home/my/day12/day12/2/virt_to_phys/hello.ko
Skipping BTF generation for /home/my/day12/day12/2/virt_to_phys/hello.ko due to unavailability of vmlinux
make[1]: Leaving directory '/usr/src/WSL2-Linux-Kernel'
my@LPPMYTD6:~/day12/day12/2/virt_to_phys$ sudo insmod hello.ko
[sudo] password for my:
insmod: ERROR: could not insert module hello.ko: Operation not permitted
my@LPPMYTD6:~/day12/day12/2/virt_to_phys$