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authorFlorian Westphal2023-02-17 23:20:06 +0100
committerGreg Kroah-Hartman2023-03-11 13:55:24 +0100
commit3dd6ac973351308d4117eda32298a9f1d68764fd (patch)
tree9bb65d2edc556f5ffcb94c598db8e7fb1db8b950 /net/ipv6
parent8291cfdfa6cd5eacfe1a5ba81b1a8cea4f086366 (diff)
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@syzkaller.appspotmail.com Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/netfilter/ip6_tables.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 2d816277f2c5..ac902f7bca47 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);