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net: ipv4: fix infinite loop on secondary addr promotion

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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: 2638eb8b50 ("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>
This commit is contained in:
Florian Westphal 2019-06-27 14:03:32 +02:00 committed by David S. Miller
parent 5b9469a285
commit 6a9e9cea4c
1 changed files with 2 additions and 1 deletions
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3
net/ipv4/devinet.c
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@ -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);
}