Re: [PATCH bpf-next 1/2] bpf: add bound tracking for BPF_MOD

kernel test robot
2023-03-05T16:49:44Z

Hi Xu,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on bpf-next/master]

url: https://github.com/intel-lab-lkp/linux/commits/Xu-Kuohai/bpf-add-bound-tracking-for-BPF_MOD/20230305-223257
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link: https://lore.kernel.org/r/20230306033119.2634976-2-xukuohai%40huaweicloud.com
patch subject: [PATCH bpf-next 1/2] bpf: add bound tracking for BPF_MOD
config: arm-randconfig-r025-20230305 (https://download.01.org/0day-ci/archive/20230306/202303060036.zK05OC5M-lkp@intel.com/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project 67409911353323ca5edf2049ef0df54132fa1ca7)
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
# install arm cross compiling tool for clang build
# apt-get install binutils-arm-linux-gnueabi
# https://github.com/intel-lab-lkp/linux/commit/e66c7bbd32e375af92c776a2b9f51be4c515ad71
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Xu-Kuohai/bpf-add-bound-tracking-for-BPF_MOD/20230305-223257
git checkout e66c7bbd32e375af92c776a2b9f51be4c515ad71
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash kernel/bpf/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202303060036.zK05OC5M-lkp@intel.com/

All warnings (new ones prefixed by >>):

kernel/bpf/verifier.c:10298:24: warning: array index 16 is past the end of the array (that has type 'u32[16]' (aka 'unsigned int[16]')) [-Warray-bounds]
meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice_rdwr]) {
^ ~~~~~~~~~~~~~~~~~~~~~~~~
kernel/bpf/verifier.c:9150:1: note: array 'special_kfunc_list' declared here
BTF_ID_LIST(special_kfunc_list)
^
include/linux/btf_ids.h:207:27: note: expanded from macro 'BTF_ID_LIST'
#define BTF_ID_LIST(name) static u32 __maybe_unused name[16];
^
>> kernel/bpf/verifier.c:11622:13: warning: comparison of distinct pointer types ('typeof ((umax)) *' (aka 'unsigned int *') and 'uint64_t *' (aka 'unsigned long long *')) [-Wcompare-distinct-pointer-types]
umax_rem = do_div(umax, val);
^~~~~~~~~~~~~~~~~
include/asm-generic/div64.h:222:28: note: expanded from macro 'do_div'
(void)(((typeof((n)) *)0) == ((uint64_t *)0)); \
~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~
kernel/bpf/verifier.c:11622:13: error: incompatible pointer types passing 'u32 *' (aka 'unsigned int *') to parameter of type 'uint64_t *' (aka 'unsigned long long *') [-Werror,-Wincompatible-pointer-types]
umax_rem = do_div(umax, val);
^~~~~~~~~~~~~~~~~
include/asm-generic/div64.h:238:22: note: expanded from macro 'do_div'
__rem = __div64_32(&(n), __base); \
^~~~
arch/arm/include/asm/div64.h:24:45: note: passing argument to parameter 'n' here
static inline uint32_t __div64_32(uint64_t *n, uint32_t base)
^
>> kernel/bpf/verifier.c:11623:13: warning: comparison of distinct pointer types ('typeof ((umin)) *' (aka 'unsigned int *') and 'uint64_t *' (aka 'unsigned long long *')) [-Wcompare-distinct-pointer-types]
umin_rem = do_div(umin, val);
^~~~~~~~~~~~~~~~~
include/asm-generic/div64.h:222:28: note: expanded from macro 'do_div'
(void)(((typeof((n)) *)0) == ((uint64_t *)0)); \
~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~
kernel/bpf/verifier.c:11623:13: error: incompatible pointer types passing 'u32 *' (aka 'unsigned int *') to parameter of type 'uint64_t *' (aka 'unsigned long long *') [-Werror,-Wincompatible-pointer-types]
umin_rem = do_div(umin, val);
^~~~~~~~~~~~~~~~~
include/asm-generic/div64.h:238:22: note: expanded from macro 'do_div'
__rem = __div64_32(&(n), __base); \
^~~~
arch/arm/include/asm/div64.h:24:45: note: passing argument to parameter 'n' here
static inline uint32_t __div64_32(uint64_t *n, uint32_t base)
^
>> kernel/bpf/verifier.c:11622:13: warning: shift count >= width of type [-Wshift-count-overflow]
umax_rem = do_div(umax, val);
^~~~~~~~~~~~~~~~~
include/asm-generic/div64.h:234:25: note: expanded from macro 'do_div'
} else if (likely(((n) >> 32) == 0)) { \
^ ~~
include/linux/compiler.h:77:40: note: expanded from macro 'likely'
# define likely(x) __builtin_expect(!!(x), 1)
^
kernel/bpf/verifier.c:11623:13: warning: shift count >= width of type [-Wshift-count-overflow]
umin_rem = do_div(umin, val);
^~~~~~~~~~~~~~~~~
include/asm-generic/div64.h:234:25: note: expanded from macro 'do_div'
} else if (likely(((n) >> 32) == 0)) { \
^ ~~
include/linux/compiler.h:77:40: note: expanded from macro 'likely'
# define likely(x) __builtin_expect(!!(x), 1)
^
5 warnings and 2 errors generated.

vim +11622 kernel/bpf/verifier.c

11606
11607 static void scalar32_min_max_mod(struct bpf_reg_state *dst_reg,
11608 struct bpf_reg_state *src_reg)
11609 {
11610 u32 val = (u32)src_reg->var_off.value; /* src_reg is const */
11611 u32 umax = dst_reg->u32_max_value;
11612 u32 umin = dst_reg->u32_min_value;
11613 u32 umax_rem, umin_rem;
11614
11615 /* dst_reg is 32-bit truncated when mod32 zero, since
11616 * adjust_scalar_min_max_vals calls zext_32_to_64 to do truncation for
11617 * all alu32 ops, here we do nothing and just return.
11618 */
11619 if (!val)
11620 return;
11621
11622 umax_rem = do_div(umax, val);
11623 umin_rem = do_div(umin, val);
11624
11625 /* no winding */
11626 if (umax - umin < val && umin_rem <= umax_rem) {
11627 dst_reg->var_off = tnum_range(umin_rem, umax_rem);
11628 dst_reg->u32_min_value = umin_rem;
11629 dst_reg->u32_max_value = umax_rem;
11630 } else {
11631 dst_reg->var_off = tnum_range(0, val - 1);
11632 dst_reg->u32_min_value = 0;
11633 dst_reg->u32_max_value = val - 1;
11634 }
11635
11636 /* cross the sign boundary */
11637 if ((s32)dst_reg->u32_min_value > (s32)dst_reg->u32_max_value) {
11638 dst_reg->s32_min_value = S32_MIN;
11639 dst_reg->s32_max_value = S32_MAX;
11640 } else {
11641 dst_reg->s32_min_value = (s32)dst_reg->u32_min_value;
11642 dst_reg->s32_max_value = (s32)dst_reg->u32_max_value;
11643 }
11644
11645 /* mark reg64 unbounded to deduce 64-bit bounds from var_off */
11646 __mark_reg64_unbounded(dst_reg);
11647 }
11648

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0-DAY CI Kernel Test Service