This is a note to let you know that I've just added the patch titled
netfilter: ebtables: fix table blob use-after-free
to the 5.15-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-ebtables-fix-table-blob-use-after-free.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 6293011fa2cce080d42afb1dd6f5b2e7d48ab4a4
Author: Florian Westphal <fw@xxxxxxxxx>
Date: Fri Feb 17 23:20:06 2023 +0100
netfilter: ebtables: fix table blob use-after-free
[ Upstream commit e58a171d35e32e6e8c37cfe0e8a94406732a331f ]
We are not allowed to return an error at this point.
Looking at the code it looks like ret is always 0 at this
point, but its not.
t = find_table_lock(net, repl->name, &ret, &ebt_mutex);
... this can return a valid table, with ret != 0.
This bug causes update of table->private with the new
blob, but then frees the blob right away in the caller.
Syzbot report:
BUG: KASAN: vmalloc-out-of-bounds in __ebt_unregister_table+0xc00/0xcd0 net/bridge/netfilter/ebtables.c:1168
Read of size 4 at addr ffffc90005425000 by task kworker/u4:4/74
Workqueue: netns cleanup_net
Call Trace:
kasan_report+0xbf/0x1f0 mm/kasan/report.c:517
__ebt_unregister_table+0xc00/0xcd0 net/bridge/netfilter/ebtables.c:1168
ebt_unregister_table+0x35/0x40 net/bridge/netfilter/ebtables.c:1372
ops_exit_list+0xb0/0x170 net/core/net_namespace.c:169
cleanup_net+0x4ee/0xb10 net/core/net_namespace.c:613
...
ip(6)tables appears to be ok (ret should be 0 at this point) but make
this more obvious.
Fixes: c58dd2dd443c ("netfilter: Can't fail and free after table replacement")
Reported-by: syzbot+f61594de72d6705aea03@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 16774559c52cb..a09b2fc11c80e 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -1090,7 +1090,7 @@ static int do_replace_finish(struct net *net, struct ebt_replace *repl,
audit_log_nfcfg(repl->name, AF_BRIDGE, repl->nentries,
AUDIT_XT_OP_REPLACE, GFP_KERNEL);
- return ret;
+ return 0;
free_unlock:
mutex_unlock(&ebt_mutex);
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 13acb687c19ab..91301dc3924a2 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -1044,7 +1044,6 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
struct xt_counters *counters;
struct ipt_entry *iter;
- ret = 0;
counters = xt_counters_alloc(num_counters);
if (!counters) {
ret = -ENOMEM;
@@ -1090,7 +1089,7 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
net_warn_ratelimited("iptables: counters copy to user failed while replacing table\n");
}
vfree(counters);
- return ret;
+ return 0;
put_module:
module_put(t->me);
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index a579ea14a69b6..7ba68388d2e1f 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1062,7 +1062,6 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
struct xt_counters *counters;
struct ip6t_entry *iter;
- ret = 0;
counters = xt_counters_alloc(num_counters);
if (!counters) {
ret = -ENOMEM;
@@ -1108,7 +1107,7 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
net_warn_ratelimited("ip6tables: counters copy to user failed while replacing table\n");
}
vfree(counters);
- return ret;
+ return 0;
put_module:
module_put(t->me);
