linux-kernel - Re: [PATCH v2] comedi: Flush partial mappings in error case

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAG48ez2T7i_qCAcGi3nZqQeT8A3x42YSdL=rWqXOUDy5Eyaf6A@mail.gmail.com>
Date: Thu, 17 Oct 2024 00:05:04 +0200
From: Jann Horn <jannh@...gle.com>
To: kernel test robot <lkp@...el.com>, Ian Abbott <abbotti@....co.uk>
Cc: H Hartley Sweeten <hsweeten@...ionengravers.com>, Frank Mori Hess <fmh6jj@...il.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, oe-kbuild-all@...ts.linux.dev, 
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v2] comedi: Flush partial mappings in error case

On Wed, Oct 16, 2024 at 8:05 PM kernel test robot <lkp@...el.com> wrote:
> [auto build test ERROR on 6485cf5ea253d40d507cd71253c9568c5470cd27]
>
> url:    https://github.com/intel-lab-lkp/linux/commits/Jann-Horn/comedi-Flush-partial-mappings-in-error-case/20241016-022809
> base:   6485cf5ea253d40d507cd71253c9568c5470cd27
> patch link:    https://lore.kernel.org/r/20241015-comedi-tlb-v2-1-cafb0e27dd9a%40google.com
> patch subject: [PATCH v2] comedi: Flush partial mappings in error case
> config: arm-randconfig-004-20241016 (https://download.01.org/0day-ci/archive/20241017/202410170111.K30oyTWa-lkp@intel.com/config)
> compiler: arm-linux-gnueabi-gcc (GCC) 14.1.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241017/202410170111.K30oyTWa-lkp@intel.com/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@...el.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202410170111.K30oyTWa-lkp@intel.com/
>
> All errors (new ones prefixed by >>):
>
>    arm-linux-gnueabi-ld: drivers/comedi/comedi_fops.o: in function `comedi_mmap':
> >> comedi_fops.c:(.text+0x4be): undefined reference to `zap_vma_ptes'

Ugh, this one is from a nommu build ("# CONFIG_MMU is not set"), it
makes sense that you can't zap PTEs when you don't have any PTEs at
all... what really impresses me about this is that the rest of the
code compiles on nommu. I'm pretty sure this codepath wouldn't
actually _work_ on nommu, but apparently compiling it works?

I don't know what the right fix is here - should the entire comedi
driver be gated on CONFIG_MMU, or only a subset of the mmap handler,
or something else?