iwlwifi: kernel panic during boot due to module load order

iwlwifi: kernel panic during boot due to module load order

[Sasha Levin]

Hi all,

Commit cc5f7e397 ("iwlwifi: implement dynamic opmode loading") causes a
kernel panic during boot in the following scenario:

1. All drivers are built-in.
2. Due to their build order, iwl_init gets called before iwl_drv_init.
3. iwl_init will call iwl_opmode_register which will iterate the new op
list, and cause a NULL ptr deref when trying to list_for_each_entry the
dev list, which won't be empty since it wasn't initialized (iwl_drv_init
wasn't called yet).

While it's possible to easily fix the actual deref, I suspect that the
init function call order is wrong. I've looked at getting it right in
the Makefile, but it seems to have specific ordering behind it, so I'd
rather not try patching it myself.

Thanks,
Sasha.

Re: iwlwifi: kernel panic during boot due to module load order

[Johannes Berg]

On Thu, 2012-06-07 at 14:34 +0200, Sasha Levin wrote:
> Hi all,
> 
> Commit cc5f7e397 ("iwlwifi: implement dynamic opmode loading") causes a
> kernel panic during boot in the following scenario:
> 
> 1. All drivers are built-in.
> 2. Due to their build order, iwl_init gets called before iwl_drv_init.
> 3. iwl_init will call iwl_opmode_register which will iterate the new op
> list, and cause a NULL ptr deref when trying to list_for_each_entry the
> dev list, which won't be empty since it wasn't initialized (iwl_drv_init
> wasn't called yet).
> 
> While it's possible to easily fix the actual deref, I suspect that the
> init function call order is wrong. I've looked at getting it right in
> the Makefile, but it seems to have specific ordering behind it, so I'd
> rather not try patching it myself.

Yeah, looks like we forgot about this part.

I think Don said he had a fix, my suggestion would be to try to just
reorder the dvm line in the iwlwifi/Makefile to the bottom of the
Makefile, or at least after obj-$(...) += iwlwifi.o.

johannes

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