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netfilter: nat: use atomic bit op to clear the _SRC_NAT_DONE_BIT

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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 <fw@strlen.de>
Signed-off-by: Liping Zhang <zlpnobody@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Liping Zhang 2017-05-21 22:38:11 +08:00 committed by Pablo Neira Ayuso
parent d2df92e98a
commit 124dffea9e
1 changed files with 1 additions and 1 deletions
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2
net/netfilter/nf_nat_core.c
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@ -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);