From 124dffea9e8e372509e055aebd118e85518fd644 Mon Sep 17 00:00:00 2001 From: Liping Zhang Date: Sun, 21 May 2017 22:38:11 +0800 Subject: [PATCH] netfilter: nat: use atomic bit op to clear the _SRC_NAT_DONE_BIT We need to clear the IPS_SRC_NAT_DONE_BIT to indicate that the ct has been removed from nat_bysource table. But unfortunately, we use the non-atomic bit operation: "ct->status &= ~IPS_NAT_DONE_MASK". So there's a race condition that we may clear the _DYING_BIT set by another CPU unexpectedly. Since we don't care about the IPS_DST_NAT_DONE_BIT, so just using clear_bit to clear the IPS_SRC_NAT_DONE_BIT is enough. Also note, this is the last user which use the non-atomic bit operation to update the confirmed ct->status. Reported-by: Florian Westphal Signed-off-by: Liping Zhang Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_nat_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c index ef0be325a0c6..6c72922d20ca 100644 --- a/net/netfilter/nf_nat_core.c +++ b/net/netfilter/nf_nat_core.c @@ -566,7 +566,7 @@ static int nf_nat_proto_clean(struct nf_conn *ct, void *data) * Else, when the conntrack is destoyed, nf_nat_cleanup_conntrack() * will delete entry from already-freed table. */ - ct->status &= ~IPS_NAT_DONE_MASK; + clear_bit(IPS_SRC_NAT_DONE_BIT, &ct->status); rhltable_remove(&nf_nat_bysource_table, &ct->nat_bysource, nf_nat_bysource_params); -- 2.20.1