@@ -1044,10 +1044,9 @@ static int do_replace_finish(struct net *net, struct ebt_replace *repl,
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,
@@ -1039,8 +1039,10 @@ 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;
@@ -1226,8 +1226,10 @@ __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;
@@ -1236,8 +1236,10 @@ __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("ip6tables: counters copy to user failed while replacing table\n");
+ }
vfree(counters);
xt_table_unlock(t);
return ret;
This is a note to let you know that I have just added a patch titled netfilter: Can't fail and free after table replacement to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.11.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 8cdb5a92d26ff773a58d5a7142ef52dbebb37b52 Mon Sep 17 00:00:00 2001 From: Thomas Graf <tgraf@suug.ch> Date: Fri, 4 Apr 2014 17:57:45 +0200 Subject: netfilter: Can't fail and free after table replacement 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@strlen.de> Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- 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(-) -- 1.9.1