5.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit cbc3a153222805d65f821e10f4f78b6afce06f86 ]
When removing an item from RCU protected list, we must prevent store-tearing, using rcu_assign_pointer() or WRITE_ONCE().
Fixes: 04f721c671656 ("tcp_metrics: Rewrite tcp_metrics_flush_all") Signed-off-by: Eric Dumazet edumazet@google.com Reviewed-by: David Ahern dsahern@kernel.org Acked-by: Neal Cardwell ncardwell@google.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/tcp_metrics.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c index e89e19a6852ce..8e76f932727a1 100644 --- a/net/ipv4/tcp_metrics.c +++ b/net/ipv4/tcp_metrics.c @@ -903,7 +903,7 @@ static void tcp_metrics_flush_all(struct net *net) match = net ? net_eq(tm_net(tm), net) : !refcount_read(&tm_net(tm)->count); if (match) { - *pp = tm->tcpm_next; + rcu_assign_pointer(*pp, tm->tcpm_next); kfree_rcu(tm, rcu_head); } else { pp = &tm->tcpm_next; @@ -944,7 +944,7 @@ static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info) if (addr_same(&tm->tcpm_daddr, &daddr) && (!src || addr_same(&tm->tcpm_saddr, &saddr)) && net_eq(tm_net(tm), net)) { - *pp = tm->tcpm_next; + rcu_assign_pointer(*pp, tm->tcpm_next); kfree_rcu(tm, rcu_head); found = true; } else {