I am using kernel 5.4 on x86_64 fro an embedded system. loading a compressed module will give the kernel log error: kernel: Module has invalid ELF structures steps to reproduce are simply: # busybox insmod nbd.ko.gz Some points: this happens with gzip and xz the util-linux insmod/modprobe work without log entry the module seems correctly loaded and works. decompressing the module (with the same busybox executable) and then loading it will lead to no log entry # (after unloading the module again) # busybox gzip -d nbd.ko.gz # busybox insmod nbd.ko I dont know if there is any functional issue, but I am tempted to raise severity since I cant rule it out either.
I also fell into the problem. I was wondering how alpine linux worked out with compressed linux modules and I finally found out that they don't use busybox's modprobe anymore... Since the decompression methods already exist in busybox, it shouldn't be too hard to implement I guess, but I'm not competent enough to do it myself.