On Wed, 2017-05-17 at 19:56 -0400, Prarit Bhargava wrote:
> nfit_init() calls nfit_mce_register() on module load. When the module
> load fails the nfit mce decoder is not unregistered. The module's
> memory is freed leaving the decoder chain referencing junk. This will
> cause panics as future registrations will reference the free'd memory.
>
> Only register the nfit mce decoder on success.
Good find! I'm wondering if registering the mce handler after the rest
of the init will leave a (small) window open where MCEs can happen but
the handler has yet to be registered.. Maybe it is inconsequential, and
we can just do this. Alternatively, if acpi_bus_register_driver fails,
then go back and unregister the mce handler..
>
> Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx>
> Cc: Jeff Moyer <jmoyer@xxxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
> Cc: Len Brown <lenb@xxxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx>
> Cc: "Lee, Chun-Yi" <joeyli.kernel@xxxxxxxxx>
> Cc: Linda Knippers <linda.knippers@xxxxxxx>
> ---
> drivers/acpi/nfit/core.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
> index 656acb5d7166..b60856b4325b 100644
> --- a/drivers/acpi/nfit/core.c
> +++ b/drivers/acpi/nfit/core.c
> @@ -3043,6 +3043,8 @@ static void acpi_nfit_notify(struct acpi_device
> *adev, u32 event)
>
> static __init int nfit_init(void)
> {
> + int ret;
> +
> BUILD_BUG_ON(sizeof(struct acpi_table_nfit) != 40);
> BUILD_BUG_ON(sizeof(struct acpi_nfit_system_address) != 56);
> BUILD_BUG_ON(sizeof(struct acpi_nfit_memory_map) != 48);
> @@ -3069,9 +3071,11 @@ static __init int nfit_init(void)
> if (!nfit_wq)
> return -ENOMEM;
>
> - nfit_mce_register();
> + ret = acpi_bus_register_driver(&acpi_nfit_driver);
> + if (!ret)
> + nfit_mce_register();
>
> - return acpi_bus_register_driver(&acpi_nfit_driver);
> + return ret;
> }
>
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