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ipv6: annotate data-races around rt->fib6_nsiblings

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rt->fib6_nsiblings can be read locklessly, add corresponding
READ_ONCE() and WRITE_ONCE() annotations.

Fixes: 66f5d6ce53 ("ipv6: replace rwlock with rcu and spinlock in fib6_table")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250725140725.3626540-5-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2025-07-25 14:07:25 +00:00 • committed by Jakub Kicinski
parent f8d8ce1b51
commit 31d7d67ba1
2 changed files with 16 additions and 9 deletions
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20
net/ipv6/ip6_fib.c
View file

@ -445,15 +445,17 @@ struct fib6_dump_arg {
static int fib6_rt_dump(struct fib6_info *rt, struct fib6_dump_arg *arg)
{
enum fib_event_type fib_event = FIB_EVENT_ENTRY_REPLACE;
unsigned int nsiblings;
int err;
if (!rt || rt == arg->net->ipv6.fib6_null_entry)
return 0;
if (rt->fib6_nsiblings)
nsiblings = READ_ONCE(rt->fib6_nsiblings);
if (nsiblings)
err = call_fib6_multipath_entry_notifier(arg->nb, fib_event,
rt,
rt->fib6_nsiblings,
nsiblings,
arg->extack);
else
err = call_fib6_entry_notifier(arg->nb, fib_event, rt,
@ -1138,7 +1140,7 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
if (rt6_duplicate_nexthop(iter, rt)) {
if (rt->fib6_nsiblings)
rt->fib6_nsiblings = 0;
WRITE_ONCE(rt->fib6_nsiblings, 0);
if (!(iter->fib6_flags & RTF_EXPIRES))
return -EEXIST;
if (!(rt->fib6_flags & RTF_EXPIRES)) {
@ -1167,7 +1169,8 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
*/
if (rt_can_ecmp &&
rt6_qualify_for_ecmp(iter))
rt->fib6_nsiblings++;
WRITE_ONCE(rt->fib6_nsiblings,
rt->fib6_nsiblings + 1);
}
if (iter->fib6_metric > rt->fib6_metric)
@ -1217,7 +1220,8 @@ next_iter:
fib6_nsiblings = 0;
list_for_each_entry_safe(sibling, temp_sibling,
&rt->fib6_siblings, fib6_siblings) {
sibling->fib6_nsiblings++;
WRITE_ONCE(sibling->fib6_nsiblings,
sibling->fib6_nsiblings + 1);
BUG_ON(sibling->fib6_nsiblings != rt->fib6_nsiblings);
fib6_nsiblings++;
}
@ -1264,7 +1268,8 @@ add:
list_for_each_entry_safe(sibling, next_sibling,
&rt->fib6_siblings,
fib6_siblings)
sibling->fib6_nsiblings--;
WRITE_ONCE(sibling->fib6_nsiblings,
sibling->fib6_nsiblings - 1);
WRITE_ONCE(rt->fib6_nsiblings, 0);
list_del_rcu(&rt->fib6_siblings);
rcu_read_lock();
@ -2014,7 +2019,8 @@ static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
notify_del = true;
list_for_each_entry_safe(sibling, next_sibling,
&rt->fib6_siblings, fib6_siblings)
sibling->fib6_nsiblings--;
WRITE_ONCE(sibling->fib6_nsiblings,
sibling->fib6_nsiblings - 1);
WRITE_ONCE(rt->fib6_nsiblings, 0);
list_del_rcu(&rt->fib6_siblings);
rt6_multipath_rebalance(next_sibling);

5
net/ipv6/route.c
View file

@ -5346,7 +5346,8 @@ static void ip6_route_mpath_notify(struct fib6_info *rt,
*/
rcu_read_lock();
if ((nlflags & NLM_F_APPEND) && rt_last && rt_last->fib6_nsiblings) {
if ((nlflags & NLM_F_APPEND) && rt_last &&
READ_ONCE(rt_last->fib6_nsiblings)) {
rt = list_first_or_null_rcu(&rt_last->fib6_siblings,
struct fib6_info,
fib6_siblings);
@ -5856,7 +5857,7 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
if (dst->lwtstate &&
lwtunnel_fill_encap(skb, dst->lwtstate, RTA_ENCAP, RTA_ENCAP_TYPE) < 0)
goto nla_put_failure;
} else if (rt->fib6_nsiblings) {
} else if (READ_ONCE(rt->fib6_nsiblings)) {
struct fib6_info *sibling;
struct nlattr *mp;