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SubjectRe: [PATCH bpf-next 2/5] bpf: Add a bpf_snprintf helper
Hi Florent,

I love your patch! Perhaps something to improve:

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

url: https://github.com/0day-ci/linux/commits/Florent-Revest/bpf-Add-a-ARG_PTR_TO_CONST_STR-argument-type/20210311-070306
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: openrisc-randconfig-r023-20210308 (attached as .config)
compiler: or1k-linux-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://github.com/0day-ci/linux/commit/c06d419a45370b897b7383625f0435873a7458fa
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Florent-Revest/bpf-Add-a-ARG_PTR_TO_CONST_STR-argument-type/20210311-070306
git checkout c06d419a45370b897b7383625f0435873a7458fa
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=openrisc

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

All warnings (new ones prefixed by >>):

kernel/bpf/verifier.c: In function 'check_func_arg':
kernel/bpf/verifier.c:4918:13: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
4918 | map_ptr = (char *)(map_addr);
| ^
kernel/bpf/verifier.c: At top level:
>> kernel/bpf/verifier.c:5735:5: warning: no previous prototype for 'check_bpf_snprintf_call' [-Wmissing-prototypes]
5735 | int check_bpf_snprintf_call(struct bpf_verifier_env *env,
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/bpf/verifier.c: In function 'check_bpf_snprintf_call':
kernel/bpf/verifier.c:5758:8: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
5758 | fmt = (char *)fmt_addr;
| ^
In file included from include/linux/bpf_verifier.h:9,
from kernel/bpf/verifier.c:12:
kernel/bpf/verifier.c: In function 'jit_subprogs':
include/linux/filter.h:363:4: warning: cast between incompatible function types from 'unsigned int (*)(const void *, const struct bpf_insn *)' to 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} [-Wcast-function-type]
363 | ((u64 (*)(u64, u64, u64, u64, u64))(x))
| ^
kernel/bpf/verifier.c:11865:16: note: in expansion of macro 'BPF_CAST_CALL'
11865 | insn->imm = BPF_CAST_CALL(func[subprog]->bpf_func) -
| ^~~~~~~~~~~~~
kernel/bpf/verifier.c: In function 'do_misc_fixups':
include/linux/filter.h:363:4: warning: cast between incompatible function types from 'void * (* const)(struct bpf_map *, void *)' to 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} [-Wcast-function-type]
363 | ((u64 (*)(u64, u64, u64, u64, u64))(x))
| ^
kernel/bpf/verifier.c:12273:17: note: in expansion of macro 'BPF_CAST_CALL'
12273 | insn->imm = BPF_CAST_CALL(ops->map_lookup_elem) -
| ^~~~~~~~~~~~~
include/linux/filter.h:363:4: warning: cast between incompatible function types from 'int (* const)(struct bpf_map *, void *, void *, u64)' {aka 'int (* const)(struct bpf_map *, void *, void *, long long unsigned int)'} to 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} [-Wcast-function-type]
363 | ((u64 (*)(u64, u64, u64, u64, u64))(x))
| ^
kernel/bpf/verifier.c:12277:17: note: in expansion of macro 'BPF_CAST_CALL'
12277 | insn->imm = BPF_CAST_CALL(ops->map_update_elem) -
| ^~~~~~~~~~~~~
include/linux/filter.h:363:4: warning: cast between incompatible function types from 'int (* const)(struct bpf_map *, void *)' to 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} [-Wcast-function-type]
363 | ((u64 (*)(u64, u64, u64, u64, u64))(x))
| ^
kernel/bpf/verifier.c:12281:17: note: in expansion of macro 'BPF_CAST_CALL'
12281 | insn->imm = BPF_CAST_CALL(ops->map_delete_elem) -
| ^~~~~~~~~~~~~
include/linux/filter.h:363:4: warning: cast between incompatible function types from 'int (* const)(struct bpf_map *, void *, u64)' {aka 'int (* const)(struct bpf_map *, void *, long long unsigned int)'} to 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} [-Wcast-function-type]
363 | ((u64 (*)(u64, u64, u64, u64, u64))(x))
| ^
kernel/bpf/verifier.c:12285:17: note: in expansion of macro 'BPF_CAST_CALL'
12285 | insn->imm = BPF_CAST_CALL(ops->map_push_elem) -
| ^~~~~~~~~~~~~
include/linux/filter.h:363:4: warning: cast between incompatible function types from 'int (* const)(struct bpf_map *, void *)' to 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} [-Wcast-function-type]
363 | ((u64 (*)(u64, u64, u64, u64, u64))(x))
| ^
kernel/bpf/verifier.c:12289:17: note: in expansion of macro 'BPF_CAST_CALL'
12289 | insn->imm = BPF_CAST_CALL(ops->map_pop_elem) -
| ^~~~~~~~~~~~~
include/linux/filter.h:363:4: warning: cast between incompatible function types from 'int (* const)(struct bpf_map *, void *)' to 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} [-Wcast-function-type]
363 | ((u64 (*)(u64, u64, u64, u64, u64))(x))
| ^
kernel/bpf/verifier.c:12293:17: note: in expansion of macro 'BPF_CAST_CALL'
12293 | insn->imm = BPF_CAST_CALL(ops->map_peek_elem) -
| ^~~~~~~~~~~~~
include/linux/filter.h:363:4: warning: cast between incompatible function types from 'int (* const)(struct bpf_map *, u32, u64)' {aka 'int (* const)(struct bpf_map *, unsigned int, long long unsigned int)'} to 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} [-Wcast-function-type]
363 | ((u64 (*)(u64, u64, u64, u64, u64))(x))
| ^
kernel/bpf/verifier.c:12297:17: note: in expansion of macro 'BPF_CAST_CALL'
12297 | insn->imm = BPF_CAST_CALL(ops->map_redirect) -
| ^~~~~~~~~~~~~


vim +/check_bpf_snprintf_call +5735 kernel/bpf/verifier.c

5734
> 5735 int check_bpf_snprintf_call(struct bpf_verifier_env *env,
5736 struct bpf_reg_state *regs)
5737 {
5738 struct bpf_reg_state *fmt_reg = &regs[BPF_REG_3];
5739 struct bpf_reg_state *data_len_reg = &regs[BPF_REG_5];
5740 struct bpf_map *fmt_map = fmt_reg->map_ptr;
5741 int err, fmt_map_off, i, fmt_cnt = 0, memcpy_cnt = 0, num_args;
5742 u64 fmt_addr;
5743 char *fmt;
5744
5745 /* data must be an array of u64 so data_len must be a multiple of 8 */
5746 if (data_len_reg->var_off.value & 7)
5747 return -EINVAL;
5748 num_args = data_len_reg->var_off.value / 8;
5749
5750 /* fmt being ARG_PTR_TO_CONST_STR guarantees that var_off is const
5751 * and map_direct_value_addr is set.
5752 */
5753 fmt_map_off = fmt_reg->off + fmt_reg->var_off.value;
5754 err = fmt_map->ops->map_direct_value_addr(fmt_map, &fmt_addr,
5755 fmt_map_off);
5756 if (err)
5757 return err;
5758 fmt = (char *)fmt_addr;
5759
5760 /* We are also guaranteed that fmt+fmt_map_off is NULL terminated, we
5761 * can focus on validating the format specifiers.
5762 */
5763 for (i = fmt_map_off; fmt[i] != '\0'; i++) {
5764 if ((!isprint(fmt[i]) && !isspace(fmt[i])) ||
5765 !isascii(fmt[i])) {
5766 verbose(env, "only printable ascii for now\n");
5767 return -EINVAL;
5768 }
5769
5770 if (fmt[i] != '%')
5771 continue;
5772
5773 if (fmt[i + 1] == '%') {
5774 i++;
5775 continue;
5776 }
5777
5778 if (fmt_cnt >= MAX_SNPRINTF_VARARGS) {
5779 verbose(env, "too many format specifiers\n");
5780 return -E2BIG;
5781 }
5782
5783 if (fmt_cnt >= num_args) {
5784 verbose(env, "not enough parameters to print\n");
5785 return -EINVAL;
5786 }
5787
5788 /* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */
5789 i++;
5790
5791 /* skip optional "[0 +-][num]" width formating field */
5792 while (fmt[i] == '0' || fmt[i] == '+' || fmt[i] == '-' ||
5793 fmt[i] == ' ')
5794 i++;
5795 if (fmt[i] >= '1' && fmt[i] <= '9') {
5796 i++;
5797 while (fmt[i] >= '0' && fmt[i] <= '9')
5798 i++;
5799 }
5800
5801 if (fmt[i] == 's') {
5802 if (memcpy_cnt >= MAX_SNPRINTF_MEMCPY) {
5803 verbose(env, "too many buffer copies\n");
5804 return -E2BIG;
5805 }
5806
5807 fmt_cnt++;
5808 memcpy_cnt++;
5809 continue;
5810 }
5811
5812 if (fmt[i] == 'p') {
5813 if (fmt[i + 1] == 0 || fmt[i + 1] == 'K' ||
5814 fmt[i + 1] == 'x' || fmt[i + 1] == 'B' ||
5815 fmt[i + 1] == 's' || fmt[i + 1] == 'S') {
5816 fmt_cnt++;
5817 continue;
5818 }
5819
5820 /* only support "%pI4", "%pi4", "%pI6" and "%pi6". */
5821 if (fmt[i + 1] != 'i' && fmt[i + 1] != 'I') {
5822 verbose(env, "invalid specifier %%p%c\n",
5823 fmt[i+1]);
5824 return -EINVAL;
5825 }
5826 if (fmt[i + 2] != '4' && fmt[i + 2] != '6') {
5827 verbose(env, "invalid specifier %%p%c%c\n",
5828 fmt[i+1], fmt[i+2]);
5829 return -EINVAL;
5830 }
5831
5832 if (memcpy_cnt >= MAX_SNPRINTF_MEMCPY) {
5833 verbose(env, "too many buffer copies\n");
5834 return -E2BIG;
5835 }
5836
5837 i += 2;
5838 fmt_cnt++;
5839 memcpy_cnt++;
5840 continue;
5841 }
5842
5843 if (fmt[i] == 'l') {
5844 i++;
5845 if (fmt[i] == 'l')
5846 i++;
5847 }
5848
5849 if (fmt[i] != 'i' && fmt[i] != 'd' && fmt[i] != 'u' &&
5850 fmt[i] != 'x' && fmt[i] != 'X') {
5851 verbose(env, "invalid format specifier %%%c\n", fmt[i]);
5852 return -EINVAL;
5853 }
5854
5855 fmt_cnt++;
5856 }
5857
5858 if (fmt_cnt != num_args) {
5859 verbose(env, "too many parameters to print\n");
5860 return -EINVAL;
5861 }
5862
5863 return 0;
5864 }
5865

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