[kees:for-next/lkdtm 11/12] drivers/misc/lkdtm/fortify.c:28 lkdtm_FORTIFIED_OBJECT() error: memcmp() '&target[1]' too small (10 vs 11)

[kees:for-next/lkdtm 11/12] drivers/misc/lkdtm/fortify.c:28 lkdtm_FORTIFIED_OBJECT() error: memcmp() '&target[1]' too small (10 vs 11)

[kernel test robot]

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CC: kbuild-all(a)lists.01.org
TO: Kees Cook <keescook@chromium.org>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/lkdtm
head:   6774078fd3d20a29c0c60b8d507c99c65a57e451
commit: aa6195344df910c48627795856bae05387272857 [11/12] lkdtm/fortify: Consolidate FORTIFY_SOURCE tests
:::::: branch date: 25 hours ago
:::::: commit date: 25 hours ago
config: microblaze-randconfig-m031-20210628 (attached as .config)
compiler: microblaze-linux-gcc (GCC) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
drivers/misc/lkdtm/fortify.c:28 lkdtm_FORTIFIED_OBJECT() error: memcmp() '&target[1]' too small (10 vs 11)

vim +28 drivers/misc/lkdtm/fortify.c

aa6195344df910 Kees Cook 2021-06-29  12  
aa6195344df910 Kees Cook 2021-06-29  13  void lkdtm_FORTIFIED_OBJECT(void)
aa6195344df910 Kees Cook 2021-06-29  14  {
aa6195344df910 Kees Cook 2021-06-29  15  	struct target {
aa6195344df910 Kees Cook 2021-06-29  16  		char a[10];
aa6195344df910 Kees Cook 2021-06-29  17  	} target[2] = {};
aa6195344df910 Kees Cook 2021-06-29  18  	/*
aa6195344df910 Kees Cook 2021-06-29  19  	 * Using volatile prevents the compiler from determining the value of
aa6195344df910 Kees Cook 2021-06-29  20  	 * 'size' at compile time. Without that, we would get a compile error
aa6195344df910 Kees Cook 2021-06-29  21  	 * rather than a runtime error.
aa6195344df910 Kees Cook 2021-06-29  22  	 */
aa6195344df910 Kees Cook 2021-06-29  23  	volatile int size = 11;
aa6195344df910 Kees Cook 2021-06-29  24  
aa6195344df910 Kees Cook 2021-06-29  25  	pr_info("trying to read past the end of a struct\n");
aa6195344df910 Kees Cook 2021-06-29  26  
aa6195344df910 Kees Cook 2021-06-29  27  	/* Store result to global to prevent the code from being eliminated */
aa6195344df910 Kees Cook 2021-06-29 @28  	fortify_scratch_space = memcmp(&target[0], &target[1], size);
aa6195344df910 Kees Cook 2021-06-29  29  
aa6195344df910 Kees Cook 2021-06-29  30  	pr_err("FAIL: fortify did not block an object overread!\n");
aa6195344df910 Kees Cook 2021-06-29  31  	pr_expected_config(CONFIG_FORTIFY_SOURCE);
aa6195344df910 Kees Cook 2021-06-29  32  }
aa6195344df910 Kees Cook 2021-06-29  33  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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