On Thu, Dec 31, 2020 at 2:04 AM Qu Wenruo <[email protected]> wrote:
> On 2020/12/31 上午8:50, Denys Vlasenko wrote:
> > On Thu, Dec 31, 2020 at 1:45 AM Qu Wenruo <[email protected]> wrote:
> >> If kernel is really going to detect compressed module, the decompression
> >> should happen before we check the ELF header, thus the error message
> >> should still be there.
> >
> > I was talking from the userspace perspective: is there a reasonable way
> > to be more careful for userspace? No, unless userspace assumes
> > that finit_module() will *never* be extended to handle .ko.gz modules.
>
> It's the spec, if finit_module() really supports compressed kernel one
> day, it breaks the spec and only then it should be considered as a
> regression (ironically)
If we go down legalese road, the spec does not say "if you supply something
which is not an ELF image, kernel will emit a scary message to the log".
I propose this simple fix:
if (not_a_good_ELF_image(image_ptr)) {
+ if (!not_GZIP_signature(image_ptr)
+ || !not_BZIP2_signature(image_ptr)
+ || !not_XZ_signature(image_ptr))
printk(KERN_ERR "Module has invalid ELF header\n");
}
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