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netfilter: x_tables: fix percpu counter block leak on error path when creating new netns

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Here is the stack where we allocate percpu counter block:

  +-< __alloc_percpu
    +-< xt_percpu_counter_alloc
      +-< find_check_entry # {arp,ip,ip6}_tables.c
        +-< translate_table

And it can be leaked on this code path:

  +-> ip6t_register_table
    +-> translate_table # allocates percpu counter block
    +-> xt_register_table # fails

there is no freeing of the counter block on xt_register_table fail.
Note: xt_percpu_counter_free should be called to free it like we do in
do_replace through cleanup_entry helper (or in __ip6t_unregister_table).

Probability of hitting this error path is low AFAICS (xt_register_table
can only return ENOMEM here, as it is not replacing anything, as we are
creating new netns, and it is hard to imagine that all previous
allocations succeeded and after that one in xt_register_table failed).
But it's worth fixing even the rare leak.

Fixes: 71ae0dff02 ("netfilter: xtables: use percpu rule counters")
Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Pavel Tikhomirov 2023-02-13 12:25:05 +08:00 committed by Pablo Neira Ayuso
parent fdf6491193
commit 0af8c09c89
3 changed files with 12 additions and 0 deletions
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4
net/ipv4/netfilter/arp_tables.c
View File

@ -1525,6 +1525,10 @@ int arpt_register_table(struct net *net,
new_table = xt_register_table(net, table, &bootstrap, newinfo);
if (IS_ERR(new_table)) {
struct arpt_entry *iter;
xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
cleanup_entry(iter, net);
xt_free_table_info(newinfo);
return PTR_ERR(new_table);
}

4
net/ipv4/netfilter/ip_tables.c
View File

@ -1741,6 +1741,10 @@ int ipt_register_table(struct net *net, const struct xt_table *table,
new_table = xt_register_table(net, table, &bootstrap, newinfo);
if (IS_ERR(new_table)) {
struct ipt_entry *iter;
xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
cleanup_entry(iter, net);
xt_free_table_info(newinfo);
return PTR_ERR(new_table);
}

4
net/ipv6/netfilter/ip6_tables.c
View File

@ -1750,6 +1750,10 @@ int ip6t_register_table(struct net *net, const struct xt_table *table,
new_table = xt_register_table(net, table, &bootstrap, newinfo);
if (IS_ERR(new_table)) {
struct ip6t_entry *iter;
xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
cleanup_entry(iter, net);
xt_free_table_info(newinfo);
return PTR_ERR(new_table);
}