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netfilter: nf_tables: Fix for endless loop when dumping ruleset
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__nf_tables_dump_rules() stores the current idx value into cb->args[0]
before returning to caller. With multiple chains present, cb->args[0] is
therefore updated after each chain's rules have been traversed. This
though causes the final nf_tables_dump_rules() run (which should return
an skb->len of zero since no rules are left to dump) to continue dumping
rules for each but the first chain. Fix this by moving the cb->args[0]
update to nf_tables_dump_rules().

With no final action to be performed anymore in
__nf_tables_dump_rules(), drop 'out_unfinished' jump label and 'rc'
variable - instead return the appropriate value directly.

Fixes: 241faec ("netfilter: nf_tables: Speed up selective rule dumps")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Phil Sutter authored and Pablo Neira Ayuso committed Jan 8, 2019
1 parent a007184 commit 310529e
Showing 1 changed file with 4 additions and 6 deletions.
10 changes: 4 additions & 6 deletions net/netfilter/nf_tables_api.c
Original file line number Diff line number Diff line change
@@ -2304,7 +2304,6 @@ static int __nf_tables_dump_rules(struct sk_buff *skb,
struct net *net = sock_net(skb->sk);
unsigned int s_idx = cb->args[0];
const struct nft_rule *rule;
int rc = 1;

list_for_each_entry_rcu(rule, &chain->rules, list) {
if (!nft_is_active(net, rule))
@@ -2321,16 +2320,13 @@ static int __nf_tables_dump_rules(struct sk_buff *skb,
NLM_F_MULTI | NLM_F_APPEND,
table->family,
table, chain, rule) < 0)
goto out_unfinished;
return 1;

nl_dump_check_consistent(cb, nlmsg_hdr(skb));
cont:
(*idx)++;
}
rc = 0;
out_unfinished:
cb->args[0] = *idx;
return rc;
return 0;
}

static int nf_tables_dump_rules(struct sk_buff *skb,
@@ -2382,6 +2378,8 @@ static int nf_tables_dump_rules(struct sk_buff *skb,
}
done:
rcu_read_unlock();

cb->args[0] = idx;
return skb->len;
}

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