Re: usercopy whitelist woe in scsi_sense_cache

[Oleksandr Natalenko]

Hi.

10.04.2018 08:35, Oleksandr Natalenko wrote:
> > - does it reproduce _without_ hardened usercopy? (I would assume yes,
> > but you'd just not get any warning until the hangs started.) If it
> > does reproduce without hardened usercopy, then a new bisect run could
> > narrow the search even more.
>
> Looks like it cannot be disabled via kernel cmdline, so I have to
> re-compile the kernel, right? I can certainly do that anyway.

Okay, I've recompiled the kernel without hardened usercopy:

[root@archlinux ~]# zgrep USERCOPY /proc/config.gz
CONFIG_X86_INTEL_USERCOPY=y
CONFIG_HAVE_HARDENED_USERCOPY_ALLOCATOR=y
# CONFIG_HARDENED_USERCOPY is not set

and I cannot reproduce the issue anymore. I/O doesn't hang regardless of 
how long I hammer it.

Eeeh? Maybe, this is a matter of some cleanup code path once the 
warn/bug condition is hit with hardening enabled? I'm just guessing here 
again.

Will work towards checking Linus' master branch nowâ

Regards,
  Oleksandr