Commit 6a9e9cea authored Jun 27, 2019 by Florian Westphal Committed by David S. Miller Jun 27, 2019

net: ipv4: fix infinite loop on secondary addr promotion



secondary address promotion causes infinite loop -- it arranges
for ifa->ifa_next to point back to itself.

Problem is that 'prev_prom' and 'last_prim' might point at the same entry,
so 'last_sec' pointer must be obtained after prev_prom->next update.

Fixes: 2638eb8b ("net: ipv4: provide __rcu annotation for ifa_list")
Reported-by: Ran Rozenstein <ranro@mellanox.com>
Reported-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 5b9469a2

net/ipv4/devinet.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -428,8 +428,9 @@ no_promotions:
		if (prev_prom) {
		struct in_ifaddr *last_sec;

		last_sec = rtnl_dereference(last_prim->ifa_next);
		rcu_assign_pointer(prev_prom->ifa_next, next_sec);

		last_sec = rtnl_dereference(last_prim->ifa_next);
		rcu_assign_pointer(promote->ifa_next, last_sec);
		rcu_assign_pointer(last_prim->ifa_next, promote);
		}

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