[openeuler:openEuler-1.0-LTS 22145/22156] net/ipv4/arp.c:1106:5: warning: comparison of distinct pointer types ('typeof (dev->addr_len) *' (aka 'unsigned char *') and 'typeof (sizeof (r->arp_ha.sa_data)) *' (aka 'unsigned long *'))

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

tree:   https://gitee.com/openeuler/kernel.git openEuler-1.0-LTS
head:   e9eac2f8ec0d6e36fe87c658851c3c77f990b098
commit: 7ad207616673722d5cf52c18d9464e0d3184ffc9 [22145/22156] arp: Prevent overflow in arp_req_get().
config: x86_64-rhel-8.3-rust (https://download.01.org/0day-ci/archive/20240419/202404192145.IFJnkcXo-lkp@intel.com/config)
compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240419/202404192145.IFJnkcXo-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/202404192145.IFJnkcXo-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> net/ipv4/arp.c:1106:5: warning: comparison of distinct pointer types ('typeof (dev->addr_len) *' (aka 'unsigned char *') and 'typeof (sizeof (r->arp_ha.sa_data)) *' (aka 'unsigned long *')) [-Wcompare-distinct-pointer-types]
    1106 |                                 min(dev->addr_len, sizeof(r->arp_ha.sa_data)));
         |                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/kernel.h:884:19: note: expanded from macro 'min'
     884 | #define min(x, y)       __careful_cmp(x, y, <)
         |                         ^~~~~~~~~~~~~~~~~~~~~~
   include/linux/kernel.h:875:24: note: expanded from macro '__careful_cmp'
     875 |         __builtin_choose_expr(__safe_cmp(x, y), \
         |                               ^~~~~~~~~~~~~~~~
   include/linux/kernel.h:865:4: note: expanded from macro '__safe_cmp'
     865 |                 (__typecheck(x, y) && __no_side_effects(x, y))
         |                  ^~~~~~~~~~~~~~~~~
   include/linux/kernel.h:851:29: note: expanded from macro '__typecheck'
     851 |                 (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
         |                            ~~~~~~~~~~~~~~ ^  ~~~~~~~~~~~~~~
   1 warning generated.


vim +1106 net/ipv4/arp.c

  1090	
  1091	/*
  1092	 *	Get an ARP cache entry.
  1093	 */
  1094	
  1095	static int arp_req_get(struct arpreq *r, struct net_device *dev)
  1096	{
  1097		__be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
  1098		struct neighbour *neigh;
  1099		int err = -ENXIO;
  1100	
  1101		neigh = neigh_lookup(&arp_tbl, &ip, dev);
  1102		if (neigh) {
  1103			if (!(neigh->nud_state & NUD_NOARP)) {
  1104				read_lock_bh(&neigh->lock);
  1105				memcpy(r->arp_ha.sa_data, neigh->ha,
> 1106					min(dev->addr_len, sizeof(r->arp_ha.sa_data)));
  1107				r->arp_flags = arp_state_to_flags(neigh);
  1108				read_unlock_bh(&neigh->lock);
  1109				r->arp_ha.sa_family = dev->type;
  1110				strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
  1111				err = 0;
  1112			}
  1113			neigh_release(neigh);
  1114		}
  1115		return err;
  1116	}
  1117	

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