This is a note to let you know that I've just added the patch titled
netfilter: Can't fail and free after table replacement
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netfilter-can-t-fail-and-free-after-table-replacement.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c58dd2dd443c26d856a168db108a0cd11c285bf3 Mon Sep 17 00:00:00 2001
From: Thomas Graf <tgraf@xxxxxxx>
Date: Fri, 4 Apr 2014 17:57:45 +0200
Subject: netfilter: Can't fail and free after table replacement
From: Thomas Graf <tgraf@xxxxxxx>
commit c58dd2dd443c26d856a168db108a0cd11c285bf3 upstream.
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@xxxxxxxxx>
Signed-off-by: Thomas Graf <tgraf@xxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/bridge/netfilter/ebtables.c | 5 ++---
net/ipv4/netfilter/arp_tables.c | 6 ++++--
net/ipv4/netfilter/ip_tables.c | 6 ++++--
net/ipv6/netfilter/ip6_tables.c | 6 ++++--
4 files changed, 14 insertions(+), 9 deletions(-)
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -1044,10 +1044,9 @@ static int do_replace_finish(struct net
if (repl->num_counters &&
copy_to_user(repl->counters, counterstmp,
repl->num_counters * sizeof(struct ebt_counter))) {
- ret = -EFAULT;
+ /* Silent error, can't fail, new table is already in place */
+ net_warn_ratelimited("ebtables: counters copy to user failed while replacing table\n");
}
- else
- ret = 0;
/* decrease module count and free resources */
EBT_ENTRY_ITERATE(table->entries, table->entries_size,
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -1039,8 +1039,10 @@ static int __do_replace(struct net *net,
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;
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -1227,8 +1227,10 @@ __do_replace(struct net *net, const char
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;
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1236,8 +1236,10 @@ __do_replace(struct net *net, const char
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("ip6tables: counters copy to user failed while replacing table\n");
+ }
vfree(counters);
xt_table_unlock(t);
return ret;
Patches currently in stable-queue which might be from tgraf@xxxxxxx are
queue-3.4/netfilter-can-t-fail-and-free-after-table-replacement.patch
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