On Fri, Feb 16, 2024 at 5:50 PM Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote: > > On Fri, Feb 16, 2024 at 05:38:55PM +0100, Rafael J. Wysocki wrote: > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > > > The ACPI custom_method debugfs interface is security-sensitive and > > concurrent access to it is broken [1]. > > > > Moreover, the recipe for preparing a customized version of a given > > control method has changed at one point due to ACPICA changes, which > > has not been reflected in its documentation, so whoever used it before > > has had to adapt and it had gone unnoticed for a long time. > > > > This interface was a bad idea to start with and its implementation is > > fragile at the design level. It's been always conceptually questionable, > > problematic from the security standpoint and implemented poorly. > > > > Patches fixing its most apparent functional issues (for example, [2]) don't > > actually address much of the above. > > > > Granted, at the time it was introduced, there was no alternative, but > > there is the AML debugger in the kernel now and there is the configfs > > interface allowing custom ACPI tables to be loaded. The former can be > > used for extensive AML debugging and the latter can be use for testing > > new AML. [3] > > > > Accordingly, drop custom_method along with its (outdated anyway) > > documentation. > > > > Link: https://lore.kernel.org/linux-acpi/20221227063335.61474-1-zh.nvgt@xxxxxxxxx/ # [1] > > https://lore.kernel.org/linux-acpi/20231111132402.4142-1-shiqiang.deng213@xxxxxxxxx/ [2] > > https://stackoverflow.com/questions/62849113/how-to-unload-an-overlay-loaded-using-acpi-config-sysfs # [3] > > I believe you missed Link: tags for 2 and 3. Obviously, you are right. That's easy to fix, though, and I'd rather not confuse people by sending a v4 just because of this. > > Reported-by: Hang Zhang <zh.nvgt@xxxxxxxxx> > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > Reviewed-by: Zhang Rui <rui.zhang@xxxxxxxxx>
