On Mon, Nov 23, 2015 at 10:52:23AM +0100, Miroslav Benes wrote:
> On Fri, 20 Nov 2015, Chris J Arges wrote:
>
> [...]
>
> > @@ -272,6 +233,7 @@ static int klp_write_object_relocations(struct module
> > *pmod,
> > struct klp_object *obj)
> > {
> > int ret;
> > + unsigned long val;
> > struct klp_reloc *reloc;
> >
> > if (WARN_ON(!klp_is_object_loaded(obj)))
> > @@ -281,29 +243,26 @@ static int klp_write_object_relocations(struct module
> > *pmod,
> > return -EINVAL;
> >
> > for (reloc = obj->relocs; reloc->name; reloc++) {
> > - if (!klp_is_module(obj)) {
> > - ret = klp_verify_vmlinux_symbol(reloc->name,
> > - reloc->val);
> > - if (ret)
> > - return ret;
> > - } else {
> > - /* module, reloc->val needs to be discovered */
> > - if (reloc->external)
> > - ret = klp_find_external_symbol(pmod,
> > - reloc->name,
> > - &reloc->val);
> > - else
> > - ret = klp_find_object_symbol(obj->mod->name,
> > - reloc->name,
> > - 0, &reloc->val);
> > - if (ret)
> > - return ret;
> > - }
> > + /* discover the address of the referenced symbol */
> > + if (reloc->external) {
> > + if (reloc->sympos > 0) {
> > + pr_err("non-zero sympos for external reloc
> > symbol '%s' is not supported\n",
> > + reloc->name);
> > + return -EINVAL;
> > + }
> > + ret = klp_find_external_symbol(pmod, reloc->name, &val);
> > + } else
> > + ret = klp_find_object_symbol(obj->mod->name,
> > + reloc->name,
> > + reloc->sympos,
> > + &val);
>
> I think this will cause an unwanted effect if a relocation is for vmlinux
> symbol. obj->mod is NULL in that case. So obj->name should be there. Can
> you test it with kpatch, Chris, please? If that is possible.
>
> Thanks,
> Miroslav
>
Yes I need to fix this, an option would be to use:
ret = klp_find_object_symbol(obj->name ? obj->name : obj->mod->name,
reloc->name, 0, &reloc->val);
Testing with kpatch will require some modifications as the structures are
different.
--chris
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