Re: [PATCH][net-next] ipv6: sanitize RCU usage on fib6_next

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

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Hi Li,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net/master]
[also build test WARNING on v5.0-rc4 next-20190222]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Li-RongQing/ipv6-sanitize-RCU-usage-on-fib6_next/20190224-083824
reproduce:
        # apt-get install sparse
        make ARCH=x86_64 allmodconfig
        make C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'

All warnings (new ones prefixed by >>):

>> net/ipv6/ip6_fib.c:1764:14: sparse: warning: incorrect type in assignment (different address spaces)
   net/ipv6/ip6_fib.c:1764:14: sparse:    expected struct fib6_info [noderef] <asn:4> *
   net/ipv6/ip6_fib.c:1764:14: sparse:    got struct fib6_info *

sparse warnings: (new ones prefixed by >>)

   net/ipv6/ip6_fib.c:1764:14: sparse: warning: incorrect type in assignment (different address spaces)
>> net/ipv6/ip6_fib.c:1764:14: sparse:    expected struct fib6_info [noderef] <asn:4> *
>> net/ipv6/ip6_fib.c:1764:14: sparse:    got struct fib6_info *

vim +1764 net/ipv6/ip6_fib.c

  1752	
  1753	static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
  1754				   struct fib6_info __rcu **rtp, struct nl_info *info)
  1755	{
  1756		struct fib6_walker *w;
  1757		struct fib6_info *rt = rcu_dereference_protected(*rtp,
  1758					    lockdep_is_held(&table->tb6_lock));
  1759		struct net *net = info->nl_net;
  1760	
  1761		RT6_TRACE("fib6_del_route\n");
  1762	
  1763		/* Unlink it */
> 1764		*rtp = rcu_dereference_protected(rt->fib6_next,
  1765					    lockdep_is_held(&rt->fib6_table->tb6_lock));
  1766	
  1767		rt->fib6_node = NULL;
  1768		net->ipv6.rt6_stats->fib_rt_entries--;
  1769		net->ipv6.rt6_stats->fib_discarded_routes++;
  1770	
  1771		/* Flush all cached dst in exception table */
  1772		rt6_flush_exceptions(rt);
  1773	
  1774		/* Reset round-robin state, if necessary */
  1775		if (rcu_access_pointer(fn->rr_ptr) == rt)
  1776			fn->rr_ptr = NULL;
  1777	
  1778		/* Remove this entry from other siblings */
  1779		if (rt->fib6_nsiblings) {
  1780			struct fib6_info *sibling, *next_sibling;
  1781	
  1782			list_for_each_entry_safe(sibling, next_sibling,
  1783						 &rt->fib6_siblings, fib6_siblings)
  1784				sibling->fib6_nsiblings--;
  1785			rt->fib6_nsiblings = 0;
  1786			list_del_init(&rt->fib6_siblings);
  1787			rt6_multipath_rebalance(next_sibling);
  1788		}
  1789	
  1790		/* Adjust walkers */
  1791		read_lock(&net->ipv6.fib6_walker_lock);
  1792		FOR_WALKERS(net, w) {
  1793			if (w->state == FWS_C && w->leaf == rt) {
  1794				RT6_TRACE("walker %p adjusted by delroute\n", w);
  1795				w->leaf = rcu_dereference_protected(rt->fib6_next,
  1796						    lockdep_is_held(&table->tb6_lock));
  1797				if (!w->leaf)
  1798					w->state = FWS_U;
  1799			}
  1800		}
  1801		read_unlock(&net->ipv6.fib6_walker_lock);
  1802	
  1803		/* If it was last route, call fib6_repair_tree() to:
  1804		 * 1. For root node, put back null_entry as how the table was created.
  1805		 * 2. For other nodes, expunge its radix tree node.
  1806		 */
  1807		if (!rcu_access_pointer(fn->leaf)) {
  1808			if (!(fn->fn_flags & RTN_TL_ROOT)) {
  1809				fn->fn_flags &= ~RTN_RTINFO;
  1810				net->ipv6.rt6_stats->fib_route_nodes--;
  1811			}
  1812			fn = fib6_repair_tree(net, table, fn);
  1813		}
  1814	
  1815		fib6_purge_rt(rt, fn, net);
  1816	
  1817		call_fib6_entry_notifiers(net, FIB_EVENT_ENTRY_DEL, rt, NULL);
  1818		if (!info->skip_notify)
  1819			inet6_rt_notify(RTM_DELROUTE, rt, info, 0);
  1820		fib6_info_release(rt);
  1821	}
  1822	

---
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