linux-kernel - Re: [PATCH v5 1/4] x86, boot: Refactor KASLR entropy functions

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Message-ID: <201605130422.vLicKyYg%fengguang.wu@intel.com>
Date:	Fri, 13 May 2016 04:18:43 +0800
From:	kbuild test robot <lkp@...el.com>
To:	Thomas Garnier <thgarnie@...gle.com>
Cc:	kbuild-all@...org, "H . Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...e.de>,
	Andy Lutomirski <luto@...nel.org>,
	Thomas Garnier <thgarnie@...gle.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Dan Williams <dan.j.williams@...el.com>,
	Kees Cook <keescook@...omium.org>,
	Stephen Smalley <sds@...ho.nsa.gov>,
	Kefeng Wang <wangkefeng.wang@...wei.com>,
	Jonathan Corbet <corbet@....net>,
	Matt Fleming <matt@...eblueprint.co.uk>,
	Toshi Kani <toshi.kani@....com>,
	Alexander Kuleshov <kuleshovmail@...il.com>,
	Alexander Popov <alpopov@...ecurity.com>,
	Joerg Roedel <jroedel@...e.de>, Dave Young <dyoung@...hat.com>,
	Baoquan He <bhe@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Mark Salter <msalter@...hat.com>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
	gthelen@...gle.com, kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH v5 1/4] x86, boot: Refactor KASLR entropy functions

Hi,

[auto build test WARNING on next-20160512]
[cannot apply to tip/x86/core v4.6-rc7 v4.6-rc6 v4.6-rc5 v4.6-rc7]
[if your patch is applied to the wrong git tree, please drop us a note to help improving the system]

url:    https://github.com/0day-ci/linux/commits/Thomas-Garnier/x86-boot-KASLR-memory-randomization/20160513-033333
config: i386-randconfig-i1-05121127 (attached as .config)
compiler: gcc-6 (Debian 6.1.1-1) 6.1.1 20160430
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All warnings (new ones prefixed by >>):

   arch/x86/boot/compressed/kaslr.c: In function 'find_random_virt_addr':
>> arch/x86/boot/compressed/kaslr.c:390:16: warning: implicit declaration of function 'get_random_long' [-Wimplicit-function-declaration]
     random_addr = get_random_long("Virtual") % slots;
                   ^~~~~~~~~~~~~~~

vim +/get_random_long +390 arch/x86/boot/compressed/kaslr.c

071a7493 Baoquan He      2016-05-09  374  {
071a7493 Baoquan He      2016-05-09  375  	unsigned long slots, random_addr;
071a7493 Baoquan He      2016-05-09  376  
071a7493 Baoquan He      2016-05-09  377  	/* Make sure minimum is aligned. */
071a7493 Baoquan He      2016-05-09  378  	minimum = ALIGN(minimum, CONFIG_PHYSICAL_ALIGN);
071a7493 Baoquan He      2016-05-09  379  	/* Align image_size for easy slot calculations. */
071a7493 Baoquan He      2016-05-09  380  	image_size = ALIGN(image_size, CONFIG_PHYSICAL_ALIGN);
071a7493 Baoquan He      2016-05-09  381  
071a7493 Baoquan He      2016-05-09  382  	/*
071a7493 Baoquan He      2016-05-09  383  	 * There are how many CONFIG_PHYSICAL_ALIGN-sized slots
071a7493 Baoquan He      2016-05-09  384  	 * that can hold image_size within the range of minimum to
071a7493 Baoquan He      2016-05-09  385  	 * KERNEL_IMAGE_SIZE?
071a7493 Baoquan He      2016-05-09  386  	 */
071a7493 Baoquan He      2016-05-09  387  	slots = (KERNEL_IMAGE_SIZE - minimum - image_size) /
071a7493 Baoquan He      2016-05-09  388  		 CONFIG_PHYSICAL_ALIGN + 1;
071a7493 Baoquan He      2016-05-09  389  
d2d3462f Kees Cook       2016-05-09 @390  	random_addr = get_random_long("Virtual") % slots;
071a7493 Baoquan He      2016-05-09  391  
071a7493 Baoquan He      2016-05-09  392  	return random_addr * CONFIG_PHYSICAL_ALIGN + minimum;
071a7493 Baoquan He      2016-05-09  393  }
071a7493 Baoquan He      2016-05-09  394  
549f90db Borislav Petkov 2016-05-06  395  /*
549f90db Borislav Petkov 2016-05-06  396   * Since this function examines addresses much more numerically,
549f90db Borislav Petkov 2016-05-06  397   * it takes the input and output pointers as 'unsigned long'.
549f90db Borislav Petkov 2016-05-06  398   */

:::::: The code at line 390 was first introduced by commit
:::::: d2d3462f9f08da364c8fbd41e8e32229d610d49d x86/KASLR: Clarify purpose of each get_random_long()

:::::: TO: Kees Cook <keescook@...omium.org>
:::::: CC: Ingo Molnar <mingo@...nel.org>

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