Re: [PATCH -next v2] nbd: add the check to prevent overflow in __nbd_ioctl()

From: kernel test robot
Date: Mon Aug 02 2021 - 07:39:12 EST


Hi Baokun,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on next-20210730]

url: https://github.com/0day-ci/linux/commits/Baokun-Li/nbd-add-the-check-to-prevent-overflow-in-__nbd_ioctl/20210802-154727
base: 8d4b477da1a807199ca60e0829357ce7aa6758d5
config: sh-randconfig-r005-20210802 (attached as .config)
compiler: sh4-linux-gcc (GCC) 10.3.0
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://github.com/0day-ci/linux/commit/db848e3e79fb93dcba9390dda472184ab2d31f40
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Baokun-Li/nbd-add-the-check-to-prevent-overflow-in-__nbd_ioctl/20210802-154727
git checkout db848e3e79fb93dcba9390dda472184ab2d31f40
# save the attached .config to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-10.3.0 make.cross O=build_dir ARCH=sh SHELL=/bin/bash drivers/block/

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

All warnings (new ones prefixed by >>):

In file included from include/asm-generic/bug.h:5,
from arch/sh/include/asm/bug.h:112,
from include/linux/bug.h:5,
from include/linux/thread_info.h:13,
from include/asm-generic/current.h:5,
from ./arch/sh/include/generated/asm/current.h:1,
from include/linux/sched.h:12,
from include/linux/blkdev.h:5,
from drivers/block/nbd.c:16:
drivers/block/nbd.c: In function '__nbd_ioctl':
>> include/linux/overflow.h:88:15: warning: comparison of distinct pointer types lacks a cast
88 | (void) (&__a == &__b); \
| ^~
include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
78 | # define unlikely(x) __builtin_expect(!!(x), 0)
| ^
drivers/block/nbd.c:1402:16: note: in expansion of macro 'check_mul_overflow'
1402 | if (unlikely(check_mul_overflow(arg, config->blksize,
| ^~~~~~~~~~~~~~~~~~
include/linux/overflow.h:89:15: warning: comparison of distinct pointer types lacks a cast
89 | (void) (&__a == __d); \
| ^~
include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
78 | # define unlikely(x) __builtin_expect(!!(x), 0)
| ^
drivers/block/nbd.c:1402:16: note: in expansion of macro 'check_mul_overflow'
1402 | if (unlikely(check_mul_overflow(arg, config->blksize,
| ^~~~~~~~~~~~~~~~~~


vim +88 include/linux/overflow.h

f0907827a8a915 Rasmus Villemoes 2018-05-08 83
9b80e4c4ddaca3 Kees Cook 2020-08-12 84 #define check_mul_overflow(a, b, d) __must_check_overflow(({ \
f0907827a8a915 Rasmus Villemoes 2018-05-08 85 typeof(a) __a = (a); \
f0907827a8a915 Rasmus Villemoes 2018-05-08 86 typeof(b) __b = (b); \
f0907827a8a915 Rasmus Villemoes 2018-05-08 87 typeof(d) __d = (d); \
f0907827a8a915 Rasmus Villemoes 2018-05-08 @88 (void) (&__a == &__b); \
f0907827a8a915 Rasmus Villemoes 2018-05-08 89 (void) (&__a == __d); \
f0907827a8a915 Rasmus Villemoes 2018-05-08 90 __builtin_mul_overflow(__a, __b, __d); \
9b80e4c4ddaca3 Kees Cook 2020-08-12 91 }))
f0907827a8a915 Rasmus Villemoes 2018-05-08 92

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0-DAY CI Kernel Test Service, Intel Corporation
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