lib/test_kasan_module.c:25:6: warning: variable 'unused' set but not used

From: kernel test robot
Date: Sun Apr 04 2021 - 14:17:09 EST

Hi Andrey,

First bad commit (maybe != root cause):

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 2023a53bdf41b7646b1d384b6816af06309f73a5
commit: 5d92bdffd2d53f98de683229c0ad7d028703fdba kasan: rename CONFIG_TEST_KASAN_MODULE
date: 6 weeks ago
config: arm-randconfig-r024-20210404 (attached as .config)
compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5d92bdffd2d53f98de683229c0ad7d028703fdba
git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout 5d92bdffd2d53f98de683229c0ad7d028703fdba
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

lib/test_kasan_module.c: In function 'copy_user_test':
>> lib/test_kasan_module.c:25:6: warning: variable 'unused' set but not used [-Wunused-but-set-variable]
25 | int unused;
| ^~~~~~


vim +/unused +25 lib/test_kasan_module.c

73228c7ecc5e40 Patricia Alfonso 2020-10-13 19
73228c7ecc5e40 Patricia Alfonso 2020-10-13 20 static noinline void __init copy_user_test(void)
73228c7ecc5e40 Patricia Alfonso 2020-10-13 21 {
73228c7ecc5e40 Patricia Alfonso 2020-10-13 22 char *kmem;
73228c7ecc5e40 Patricia Alfonso 2020-10-13 23 char __user *usermem;
73228c7ecc5e40 Patricia Alfonso 2020-10-13 24 size_t size = 10;
73228c7ecc5e40 Patricia Alfonso 2020-10-13 @25 int unused;
73228c7ecc5e40 Patricia Alfonso 2020-10-13 26
73228c7ecc5e40 Patricia Alfonso 2020-10-13 27 kmem = kmalloc(size, GFP_KERNEL);
73228c7ecc5e40 Patricia Alfonso 2020-10-13 28 if (!kmem)
73228c7ecc5e40 Patricia Alfonso 2020-10-13 29 return;
73228c7ecc5e40 Patricia Alfonso 2020-10-13 30
73228c7ecc5e40 Patricia Alfonso 2020-10-13 31 usermem = (char __user *)vm_mmap(NULL, 0, PAGE_SIZE,
73228c7ecc5e40 Patricia Alfonso 2020-10-13 32 PROT_READ | PROT_WRITE | PROT_EXEC,
73228c7ecc5e40 Patricia Alfonso 2020-10-13 33 MAP_ANONYMOUS | MAP_PRIVATE, 0);
73228c7ecc5e40 Patricia Alfonso 2020-10-13 34 if (IS_ERR(usermem)) {
73228c7ecc5e40 Patricia Alfonso 2020-10-13 35 pr_err("Failed to allocate user memory\n");
73228c7ecc5e40 Patricia Alfonso 2020-10-13 36 kfree(kmem);
73228c7ecc5e40 Patricia Alfonso 2020-10-13 37 return;
73228c7ecc5e40 Patricia Alfonso 2020-10-13 38 }
73228c7ecc5e40 Patricia Alfonso 2020-10-13 39
73228c7ecc5e40 Patricia Alfonso 2020-10-13 40 pr_info("out-of-bounds in copy_from_user()\n");
73228c7ecc5e40 Patricia Alfonso 2020-10-13 41 unused = copy_from_user(kmem, usermem, size + 1 + OOB_TAG_OFF);
73228c7ecc5e40 Patricia Alfonso 2020-10-13 42
73228c7ecc5e40 Patricia Alfonso 2020-10-13 43 pr_info("out-of-bounds in copy_to_user()\n");
73228c7ecc5e40 Patricia Alfonso 2020-10-13 44 unused = copy_to_user(usermem, kmem, size + 1 + OOB_TAG_OFF);
73228c7ecc5e40 Patricia Alfonso 2020-10-13 45
73228c7ecc5e40 Patricia Alfonso 2020-10-13 46 pr_info("out-of-bounds in __copy_from_user()\n");
73228c7ecc5e40 Patricia Alfonso 2020-10-13 47 unused = __copy_from_user(kmem, usermem, size + 1 + OOB_TAG_OFF);
73228c7ecc5e40 Patricia Alfonso 2020-10-13 48
73228c7ecc5e40 Patricia Alfonso 2020-10-13 49 pr_info("out-of-bounds in __copy_to_user()\n");
73228c7ecc5e40 Patricia Alfonso 2020-10-13 50 unused = __copy_to_user(usermem, kmem, size + 1 + OOB_TAG_OFF);
73228c7ecc5e40 Patricia Alfonso 2020-10-13 51
73228c7ecc5e40 Patricia Alfonso 2020-10-13 52 pr_info("out-of-bounds in __copy_from_user_inatomic()\n");
73228c7ecc5e40 Patricia Alfonso 2020-10-13 53 unused = __copy_from_user_inatomic(kmem, usermem, size + 1 + OOB_TAG_OFF);
73228c7ecc5e40 Patricia Alfonso 2020-10-13 54
73228c7ecc5e40 Patricia Alfonso 2020-10-13 55 pr_info("out-of-bounds in __copy_to_user_inatomic()\n");
73228c7ecc5e40 Patricia Alfonso 2020-10-13 56 unused = __copy_to_user_inatomic(usermem, kmem, size + 1 + OOB_TAG_OFF);
73228c7ecc5e40 Patricia Alfonso 2020-10-13 57
73228c7ecc5e40 Patricia Alfonso 2020-10-13 58 pr_info("out-of-bounds in strncpy_from_user()\n");
73228c7ecc5e40 Patricia Alfonso 2020-10-13 59 unused = strncpy_from_user(kmem, usermem, size + 1 + OOB_TAG_OFF);
73228c7ecc5e40 Patricia Alfonso 2020-10-13 60
73228c7ecc5e40 Patricia Alfonso 2020-10-13 61 vm_munmap((unsigned long)usermem, PAGE_SIZE);
73228c7ecc5e40 Patricia Alfonso 2020-10-13 62 kfree(kmem);
73228c7ecc5e40 Patricia Alfonso 2020-10-13 63 }
73228c7ecc5e40 Patricia Alfonso 2020-10-13 64

:::::: The code at line 25 was first introduced by commit
:::::: 73228c7ecc5e40c0851c4703c5ec6ed38123e989 KASAN: port KASAN Tests to KUnit

:::::: TO: Patricia Alfonso <trishalfonso@xxxxxxxxxx>
:::::: CC: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>

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

Attachment: .config.gz
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