Re: BUG: unable to handle kernel paging request in hmac_init_tfm

[Eric Biggers]

On Thu, Dec 21, 2017 at 08:44:03AM +0100, 'Dmitry Vyukov' via syzkaller-bugs wrote:
> On Thu, Dec 21, 2017 at 12:09 AM, Eric Biggers <ebiggers3@xxxxxxxxx> wrote:
> > On Mon, Dec 18, 2017 at 11:36:01AM -0800, syzbot wrote:
> >> Hello,
> >>
> >> syzkaller hit the following crash on
> >> 6084b576dca2e898f5c101baef151f7bfdbb606d
> >> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
> >> compiler: gcc (GCC) 7.1.1 20170620
> >> .config is attached
> >
> > FYI, in linux-next KASAN and other memory debugging options are now behind
> > CONFIG_DEBUG_MEMORY.  So, I think KASAN isn't getting turned on anymore, despite
> > the CONFIG_KASAN=y.  (Patch was "lib/: make "Memory Debugging" a menuconfig to
> > ease disabling it all".)
> 
> Ouch! That would be pretty bad.
> 
> But I've tried both linux-next HEAD at:
> 
> commit 0e08c463db387a2adcb0243b15ab868a73f87807 (HEAD, tag:
> next-20171221, linux-next/master)
> Author: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> Date:   Thu Dec 21 15:37:39 2017 +1100
>     Add linux-next specific files for 20171221
> 
> and mmots HEAD at:
> 
> commit 75aa5540627fdb3d8f86229776ea87f995275351 (HEAD, tag:
> v4.15-rc4-mmots-2017-12-20-19-10, mmots/master)
> Author: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Date:   Thu Dec 21 04:02:17 2017 +0000
>     pci: test for unexpectedly disabled bridges
> 
> and after running make olddefconfig I still see CONFIG_KASAN=y in
> .config, nor I can find CONFIG_DEBUG_MEMORY in menuconfig.
> 
> What am I missing? What commit has added the config?
> 

Ah, I see the patch was added to -mm on 2017-12-12 but removed two days later:

https://www.spinics.net/lists/mm-commits/msg129685.html
https://www.spinics.net/lists/mm-commits/msg129696.html

So it was in linux-next temporarily (including the kernel version used for this
particular bug report) but now it's not.  Just keep an eye out for it coming
back, I guess.

Eric