Re: [PATCH v2] kasan: Disable branch tracing for core runtime

From: Andrew Morton
Date: Fri May 22 2020 - 19:42:58 EST


On Fri, 22 May 2020 09:52:07 +0200 Marco Elver <elver@xxxxxxxxxx> wrote:

> During early boot, while KASAN is not yet initialized, it is possible to
> enter reporting code-path and end up in kasan_report(). While
> uninitialized, the branch there prevents generating any reports,
> however, under certain circumstances when branches are being traced
> (TRACE_BRANCH_PROFILING), we may recurse deep enough to cause kernel
> reboots without warning.
>
> To prevent similar issues in future, we should disable branch tracing
> for the core runtime.
>
> Link: 20200517011732.GE24705@shao2-debian/">https://lore.kernel.org/lkml/20200517011732.GE24705@shao2-debian/
> Reported-by: kernel test robot <rong.a.chen@xxxxxxxxx>
> Signed-off-by: Marco Elver <elver@xxxxxxxxxx>

I assume this affects 5.6 and perhaps earlier kernels?

I also assume that a cc:stable is appropriate for this fix?