Re: [PATCH v2] acpi: fix acpi_get_table() leak / acpi-sysfs denial of service

[Dan Williams]

On Wed, Apr 26, 2017 at 3:37 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> On Wed, Apr 26, 2017 at 3:25 PM, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
>> On Tue, Apr 25, 2017 at 9:58 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
>>> Reading an ACPI table through the /sys/firmware/acpi/tables interface
>>> more than 65,536 times leads to the following log message:
>>>
>>>  ACPI Error: Table ffff88033595eaa8, Validation count is zero after increment
>>>   (20170119/tbutils-423)
>>>
>>> ...and the table being unavailable until the next reboot. Add the
>>> missing acpi_put_table() so the table ->validation_count is decremented
>>> after each read.
>>>
>>> Cc: <stable@xxxxxxxxxxxxxxx>
>>> Cc: Zhang Rui <rui.zhang@xxxxxxxxx>
>>> Cc: Rafael Wysocki <rafael.j.wysocki@xxxxxxxxx>
>>> Cc: Kristin Jacque <kristin.jacque@xxxxxxxxx>
>>> Cc: Tiffany Kasanicky <tiffany.j.kasanicky@xxxxxxxxx>
>>> Cc: Ryon Jensen <ryon.jensen@xxxxxxxxx>
>>> Reported-by: Anush Seetharaman <anush.seetharaman@xxxxxxxxx>
>>> Fixes: 1c8fce27e275 ("ACPI: introduce drivers/acpi/sysfs.c")
>>> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
>>
>> I'm going to apply this, but your Fixes tag is not correct.
>>
>> validation_count was added to struct acpi_table_desc by commit
>>
>> commit 174cc7187e6f088942c8e74daa7baff7b44b33c9
>> Author: Lv Zheng <lv.zheng@xxxxxxxxx>
>> Date:   Wed Dec 14 15:04:25 2016 +0800
>>
>>     ACPICA: Tables: Back port acpi_get_table_with_size() and
>> early_acpi_os_unmap_memory()
>> from Linux kernel
>>
>> from the 4.10 time frame, so IMO it should be
>>
>> Fixes: 174cc7187e6f (ACPICA: Tables: Back port
>> acpi_get_table_with_size() and early_acpi_os_unmap_memory() from Linux
>> kernel)
>>
>
> Ah, thanks for the catch, I missed that detail and was wrong to argue
> it was a 7 year old bug. Apologies Lv!

Hi Rafael, I don't see this in latest Linus master or queued in your
bleeding-edge branch.