Re: [RFC PATCH bpf-next] bpf: Support L4 csum update for IPv6 address changes

[kernel test robot <lkp@intel.com>]

Hi Paul,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build warnings:

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

url:    https://github.com/intel-lab-lkp/linux/commits/Paul-Chaignon/bpf-Support-L4-csum-update-for-IPv6-address-changes/20250521-060705
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/aCz84JU60wd8etiT%40mail.gmail.com
patch subject: [RFC PATCH bpf-next] bpf: Support L4 csum update for IPv6 address changes
config: arc-randconfig-001-20250521 (https://download.01.org/0day-ci/archive/20250521/202505212155.GD0kA7Jj-lkp@intel.com/config)
compiler: arc-linux-gcc (GCC) 10.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250521/202505212155.GD0kA7Jj-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202505212155.GD0kA7Jj-lkp@intel.com/

All warnings (new ones prefixed by >>):

   net/core/filter.c: In function '____bpf_l4_csum_replace':
>> net/core/filter.c:1990:40: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
    1990 |    inet_proto_csum_replace16(ptr, skb, (void *)from, (void *)to, is_pseudo);
         |                                        ^
   net/core/filter.c:1990:54: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
    1990 |    inet_proto_csum_replace16(ptr, skb, (void *)from, (void *)to, is_pseudo);
         |                                                      ^


vim +1990 net/core/filter.c

  1964	
  1965	BPF_CALL_5(bpf_l4_csum_replace, struct sk_buff *, skb, u32, offset,
  1966		   u64, from, u64, to, u64, flags)
  1967	{
  1968		bool is_pseudo    = flags & BPF_F_PSEUDO_HDR;
  1969		bool is_mmzero    = flags & BPF_F_MARK_MANGLED_0;
  1970		bool do_mforce    = flags & BPF_F_MARK_ENFORCE;
  1971		bool is_ipv6_addr = flags & BPF_F_IPV6_ADDR;
  1972		__sum16 *ptr;
  1973	
  1974		if (unlikely(flags & ~(BPF_F_MARK_MANGLED_0 | BPF_F_MARK_ENFORCE |
  1975				       BPF_F_PSEUDO_HDR | BPF_F_HDR_FIELD_MASK |
  1976				       BPF_F_IPV6_ADDR)))
  1977			return -EINVAL;
  1978		if (unlikely(offset > 0xffff || offset & 1))
  1979			return -EFAULT;
  1980		if (unlikely(bpf_try_make_writable(skb, offset + sizeof(*ptr))))
  1981			return -EFAULT;
  1982	
  1983		ptr = (__sum16 *)(skb->data + offset);
  1984		if (is_mmzero && !do_mforce && !*ptr)
  1985			return 0;
  1986	
  1987		switch (flags & BPF_F_HDR_FIELD_MASK) {
  1988		case 0:
  1989			if (is_ipv6_addr) {
> 1990				inet_proto_csum_replace16(ptr, skb, (void *)from, (void *)to, is_pseudo);
  1991			} else {
  1992				if (unlikely(from != 0))
  1993					return -EINVAL;
  1994				inet_proto_csum_replace_by_diff(ptr, skb, to, is_pseudo);
  1995			}
  1996			break;
  1997		case 2:
  1998			inet_proto_csum_replace2(ptr, skb, from, to, is_pseudo);
  1999			break;
  2000		case 4:
  2001			inet_proto_csum_replace4(ptr, skb, from, to, is_pseudo);
  2002			break;
  2003		default:
  2004			return -EINVAL;
  2005		}
  2006	
  2007		if (is_mmzero && !*ptr)
  2008			*ptr = CSUM_MANGLED_0;
  2009		return 0;
  2010	}
  2011	

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