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authorThomas Graf <tgraf@suug.ch>2014-04-04 17:57:45 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2014-04-05 17:46:22 +0200
commitc58dd2dd443c26d856a168db108a0cd11c285bf3 (patch)
treefc3b89ed8e66d3f99f9322efc812e8c7bcd60509 /net/ipv4
parent2fec6bb6f484b1a88b4a325724234d6cfd08c918 (diff)
netfilter: Can't fail and free after table replacement
All xtables variants suffer from the defect that the copy_to_user() to copy the counters to user memory may fail after the table has already been exchanged and thus exposed. Return an error at this point will result in freeing the already exposed table. Any subsequent packet processing will result in a kernel panic. We can't copy the counters before exposing the new tables as we want provide the counter state after the old table has been unhooked. Therefore convert this into a silent error. Cc: Florian Westphal <fw@strlen.de> Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/netfilter/arp_tables.c6
-rw-r--r--net/ipv4/netfilter/ip_tables.c6
2 files changed, 8 insertions, 4 deletions
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 59da7cde072..f95b6f93814 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -1044,8 +1044,10 @@ static int __do_replace(struct net *net, const char *name,
xt_free_table_info(oldinfo);
if (copy_to_user(counters_ptr, counters,
- sizeof(struct xt_counters) * num_counters) != 0)
- ret = -EFAULT;
+ sizeof(struct xt_counters) * num_counters) != 0) {
+ /* Silent error, can't fail, new table is already in place */
+ net_warn_ratelimited("arptables: counters copy to user failed while replacing table\n");
+ }
vfree(counters);
xt_table_unlock(t);
return ret;
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 718dfbd30cb..99e810f8467 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -1231,8 +1231,10 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
xt_free_table_info(oldinfo);
if (copy_to_user(counters_ptr, counters,
- sizeof(struct xt_counters) * num_counters) != 0)
- ret = -EFAULT;
+ sizeof(struct xt_counters) * num_counters) != 0) {
+ /* Silent error, can't fail, new table is already in place */
+ net_warn_ratelimited("iptables: counters copy to user failed while replacing table\n");
+ }
vfree(counters);
xt_table_unlock(t);
return ret;