Re: [PATCH v24 12/12] LRNG - add interface for gathering of raw entropy

From: "Stephan Müller" <smueller@chronox.de>
To: kbuild test robot <lkp@intel.com>
Cc: kbuild-all@lists.01.org, Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-crypto@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	linux-api@vger.kernel.org,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	"Alexander E. Patrakov" <patrakov@gmail.com>,
	"Ahmed S. Darwish" <darwish.07@gmail.com>,
	"Theodore Y. Ts'o" <tytso@mit.edu>, Willy Tarreau <w@1wt.eu>,
	Matthew Garrett <mjg59@srcf.ucam.org>,
	Vito Caputo <vcaputo@pengaru.com>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	Jan Kara <jack@suse.cz>, Ray Strode <rstrode@redhat.com>,
	William Jon McCann <mccann@jhu.edu>,
	zhangjs <zachary@baishancloud.com>,
	Andy Lutomirski <luto@kernel.org>,
	Florian Weimer <fweimer@redhat.com>,
	Lennart Poettering <mzxreary@0pointer.de>,
	Nicolai Stange <nstange@suse.de>,
	"Peter, Matthias" <matthias.peter@bsi.bund.de>,
	Marcelo Henrique Cerri <marcelo.cerri@canonical.com>,
	Roman Drahtmueller <draht@schaltsekun.de>,
	Neil Horman <nhorman@redhat.com>
Subject: Re: [PATCH v24 12/12] LRNG - add interface for gathering of raw entropy
Date: Wed, 13 Nov 2019 00:13:09 +0100
Message-ID: <16924163.rk3kQpxnsR@positron.chronox.de> (raw)
In-Reply-To: <201911130440.pXLcGJwR%lkp@intel.com>

Am Dienstag, 12. November 2019, 21:55:10 CET schrieb kbuild test robot:

Hi kbuild,

> Hi "Stephan,
> 
> Thank you for the patch! Perhaps something to improve:
> 
> [auto build test WARNING on char-misc/char-misc-testing]
> [also build test WARNING on v5.4-rc7 next-20191111]
> [if your patch is applied to the wrong git tree, please drop us a note to
> help improve the system. BTW, we also suggest to use '--base' option to
> specify the base tree in git format-patch, please see
> https://stackoverflow.com/a/37406982]
> 
> url:   
> https://github.com/0day-ci/linux/commits/Stephan-M-ller/dev-random-a-new-ap
> proach-with-full-SP800-90B-compliance/20191113-040847 base:  
> https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
> 01b59c763fe2de845b65900485b141fdd7bbf93e config: sh-allmodconfig (attached
> as .config)
> compiler: sh4-linux-gcc (GCC) 7.4.0
> reproduce:
>         wget
> https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
> ~/bin/make.cross chmod +x ~/bin/make.cross
>         # save the attached .config to linux build tree
>         GCC_VERSION=7.4.0 make.cross ARCH=sh
> 
> If you fix the issue, kindly add following tag
> Reported-by: kbuild test robot <lkp@intel.com>
> 
> All warnings (new ones prefixed by >>):
> 
>    drivers/char/lrng/lrng_testing.c: In function 'lrng_raw_extract_user':
> >> drivers/char/lrng/lrng_testing.c:237:1: warning: the frame size of 1076
> >> bytes is larger than 1024 bytes [-Wframe-larger-than=]
>     }
>     ^
> 
> vim +237 drivers/char/lrng/lrng_testing.c
> 
>    196
>   
> 197	/**********************************************************************
> **** 198	 * Debugfs interface
>    199	
> **************************************************************************/
> 200	static int lrng_raw_extract_user(void __user *buf, size_t nbytes) 201	{
>    202		u8 tmp[LRNG_TESTING_RINGBUFFER_SIZE] 
__aligned(sizeof(u32));

This is the offending line.

I will need to kzalloc the code here.

Thank you.

>    203		int ret = 0, large_request = (nbytes > 256);
>    204
>    205		while (nbytes) {
>    206			int i;
>    207
>    208			if (large_request && need_resched()) {
>    209				if (signal_pending(current)) {
>    210					if (ret == 0)
>    211						ret = -ERESTARTSYS;
>    212					break;
>    213				}
>    214				schedule();
>    215			}
>    216
>    217			i = min_t(int, nbytes, sizeof(tmp));
>    218			i = lrng_raw_entropy_reader(tmp, i);
>    219			if (i <= 0) {
>    220				if (i < 0)
>    221					ret = i;
>    222				break;
>    223			}
>    224			if (copy_to_user(buf, tmp, i)) {
>    225				ret = -EFAULT;
>    226				break;
>    227			}
>    228
>    229			nbytes -= i;
>    230			buf = (u8 *)buf + i;
>    231			ret += i;
>    232		}
>    233
>    234		memzero_explicit(tmp, sizeof(tmp));
>    235
>    236		return ret;
> 
>  > 237	}
> 
>    238
> 
> ---
> 0-DAY kernel test infrastructure                 Open Source Technology
> Center https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org Intel
> Corporation

Ciao
Stephan