Re: [PATCH] ACPICA: Fix use-after-free in acpi_ps_parse_aml()

[Rafael J. Wysocki]

On Wed, Oct 19, 2022 at 9:38 AM Chen Zhongjin <chenzhongjin@xxxxxxxxxx> wrote:
>
> KASAN reports a use-after-free problem and causes kernel panic
> triggered by: modprobe acpiphp_ibm
>
> BUG: KASAN:
> use-after-free in acpi_ds_dump_method_stack (drivers/acpi/acpica/dsdebug.c:145)
> Read of size 8 at addr ffff888002f843f0 by task modprobe/519
>
> CPU: 2 PID: 519 Comm: modprobe Not tainted 6.0.0+
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
>     Call Trace:
>     <TASK>
>     acpi_ds_dump_method_stack (drivers/acpi/acpica/dsdebug.c:145)
>     acpi_ds_method_error (drivers/acpi/acpica/dsmethod.c:232)
>     acpi_ps_parse_aml (drivers/acpi/acpica/psparse.c:607)
>     ...
>     </TASK>
>
>     Allocated by task 519:
>     ...
>     __kasan_kmalloc (mm/kasan/common.c:526)
>     acpi_ds_create_walk_state (drivers/acpi/acpica/dswstate.c:519)
>     acpi_ds_call_control_method (drivers/acpi/acpica/dsmethod.c:498)
>     acpi_ps_parse_aml (drivers/acpi/acpica/psparse.c:607)
>     ...
>
>     Freed by task 519:
>     ...
>     __kmem_cache_free+0xb6/0x3c0
>     acpi_ds_delete_walk_state (drivers/acpi/acpica/dswstate.c:722)
>     acpi_ds_call_control_method (drivers/acpi/acpica/dsmethod.c:586)
>     acpi_ps_parse_aml (drivers/acpi/acpica/psparse.c:607)
>     ...
> ---[ end Kernel panic - not syncing: Fatal exception ]---
>
> In the error path in acpi_ps_parse_aml():
>
>     acpi_ds_call_control_method()
>         acpi_ds_create_walk_state()
>             acpi_ds_push_walk_state()
>             # thread->walk_state_list = walk_state
>
>         acpi_ds_init_aml_walk # *fail*
>         goto cleanup:
>         acpi_ds_delete_walk_state() # ACPI_FREE(walk_state)
>
>     acpi_ds_method_error()
>         acpi_ds_dump_method_stack()
>         # using freed thread->walk_state_list
>
> Briefly, the walk_state is pushed to thread, and freed without being poped.
> Then it is used in acpi_ds_dump_method_stack() and causes use-after-free.
>
> Add acpi_ds_pop_walk_state(thread) to the error path to fix the problem.
>
> Fixes: 0bac4295526c ("ACPICA: Dispatcher: Move stack traversal code to dispatcher")
>
> Signed-off-by: Chen Zhongjin <chenzhongjin@xxxxxxxxxx>

This should be submitted to the upstream project on GitHub, but it
looks bad enough, so I'll take care of this.

Applied as 6.1-rc material, thanks!

> ---
>  drivers/acpi/acpica/dsmethod.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/acpi/acpica/dsmethod.c b/drivers/acpi/acpica/dsmethod.c
> index ae2e768830bf..19da7fc73186 100644
> --- a/drivers/acpi/acpica/dsmethod.c
> +++ b/drivers/acpi/acpica/dsmethod.c
> @@ -581,6 +581,7 @@ acpi_ds_call_control_method(struct acpi_thread_state *thread,
>
>         acpi_ds_terminate_control_method(obj_desc, next_walk_state);
>         acpi_ds_delete_walk_state(next_walk_state);
> +       acpi_ds_pop_walk_state(thread);
>
>         return_ACPI_STATUS(status);
>  }
> --

Bob, this looks correct to me, but I may be missing something in which
case please let me know.