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SubjectRe: PATCH [1/1]: Don't return symbol lables in init sections after they have been freed
On Tue, Mar 04, 2008 at 04:05:01PM -0800, Andrew Morton wrote:
> On Tue, 4 Mar 2008 18:47:15 -0500
> Robin Getz <rgetz@blackfin.uclinux.org> wrote:
>
> > From: Robin Getz <rgetz@blackfin.uclinux.org>
> >
> > Today, when module names are looked up, we do not qualify them (check to see
> > if the init section is still active or not). This can lead to problems when
> > kernel modules get loaded into the same address that the kernel init section
> > (or other module's init section was at). We sometimes return the old / no
> > lomnger there
> >
> > This leads to bogus OOPS messages, and developers wasting their time looking
> > for problems (in the kernel init section) where there are none (since it was
> > a module).
> >
> > This patch qualifies the addresses, to make sure the addresses are still valid
> > before label/offset.
> >
> > Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
> >
> > ---
> >
> > linux-2.6.x/kernel/kallsyms.c | 3 ++-
> > linux-2.6.x/kernel/module.c | 3 ++-
> > 2 files changed, 4 insertions(+), 2 deletions(-)
> >
> > Index: linux-2.6.x/kernel/kallsyms.c
> > ===================================================================
> > --- linux-2.6.x/kernel/kallsyms.c (revision 4212)
> > +++ linux-2.6.x/kernel/kallsyms.c (working copy)
> > @@ -42,7 +42,8 @@
> >
> > static inline int is_kernel_inittext(unsigned long addr)
> > {
> > - if (addr >= (unsigned long)_sinittext
> > + if (system_state == SYSTEM_BOOTING
> > + && addr >= (unsigned long)_sinittext
> > && addr <= (unsigned long)_einittext)
> > return 1;
> > return 0;
> > Index: linux-2.6.x/kernel/module.c
> > ===================================================================
> > --- linux-2.6.x/kernel/module.c (revision 4212)
> > +++ linux-2.6.x/kernel/module.c (working copy)
> > @@ -2121,7 +2121,8 @@
> > struct module *mod;
> >
> > list_for_each_entry(mod, &modules, list) {
> > - if (within(addr, mod->module_init, mod->init_size)
> > + if ((within(addr, mod->module_init, mod->init_size)
> > + && mod->state == MODULE_STATE_COMING)
> > || within(addr, mod->module_core, mod->core_size)) {
> > if (modname)
> > *modname = mod->name;
>
> Both of the above additions could do with a comment explaining what's going
> on.
>
> The first one perhaps should use the more specific initmem_now_dynamic
> which is added by
> gregkh-driver-warn-when-statically-allocated-kobjects-are-used.patch from
> Greg's driver tree. If the intent is to merge that - if not perhaps it can
> be split up.

The intent wasn't to merge that, as it seemed like a big hack. But if
people don't mind, I have no objection to it going in.

thanks,

greg k-h


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