Re: [PATCH] acpi / apei: fix NULL deref during init

From: Thomas Schoebel-Theuer
Date: Fri Dec 14 2018 - 16:27:48 EST

On 12/14/18 21:24, Borislav Petkov wrote:

Because apei_resources_fini() happens under the same condition check and
if arch_apei_filter_addr was false, it should not become true, all of a
sudden. Or?

Hi Borislav,

please take a look at the stacktrace. For some reason, and only at that specific hardware, the condition is false, there but later the indicated error exit is taken whose message you can see immediately before the stack trace.

So this should documents the one observed case where the NULL deref is actually happening.

Of course, it would be possible to develop another solution, but this one appears the simplest and safest to me (minimum changes to the logic).

I have tested the patch on that specifc hardware: I have verified that the patch does not trigger the NULL deref anymore.

Of course, on any other hardware we have tested, the bug did not trigger at all.

If you don't have that specific hardware, you probably cannot easily trigger / verify the problem.

If you need access to the specfic hardware, talk to me in a private conversation.