On 13 March 2018 at 17:13, Alexander Sverdlin
> Hello Ard,
> On 13/03/18 17:12, Ard Biesheuvel wrote:
>>> u32 get_module_plt(struct module *mod, unsigned long loc, Elf32_Addr val)
>>> struct mod_plt_sec *pltsec = !in_init(mod, loc) ? &mod->arch.core :
>>> + struct plt_entries *plt;
>>> + int idx;
>>> - struct plt_entries *plt = (struct plt_entries
> ^^^^^^^^^^^ (*)
>>> - int idx = 0;
>>> + /* cache the address, ELF header is available only during module
>>> load */
>>> + if (!pltsec->plt_ent)
>>> + pltsec->plt_ent = (struct plt_entries
>>> + plt = pltsec->plt_ent;
>> Where is plt_ent ever used?
> Above is exactly the place it's used.
> I need to cache it because after the module load is finished the ELF header
> is freed,
> pltsec->plt pointer (*) is not valid any more.
> With the above modification it's possible to call the function during the
> whole life
> time of the module.
Right, ok. That's a problem.
This means that you are relying on get_module_plt() being called at
least once at module load time, which is not guaranteed.
Instead, you should set this member (and perhaps the entire prealloc
routine) in a module_finalize() implementation.
>>> + if (!pltsec->plt_count)
>>> + prealloc_fixed(pltsec, plt);
> I'll prepare v5 based on your other comments.
> Best regards,
> Alexander Sverdlin.