From 743a5a951d4da68d0210a53bf4327b92153f5143 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Sat, 6 Apr 2019 08:26:52 +0300 Subject: [PATCH] netfilter: nf_tables: prevent shift wrap in nft_chain_parse_hook() [ Upstream commit 33d1c018179d0a30c39cc5f1682b77867282694b ] I believe that "hook->num" can be up to UINT_MAX. Shifting more than 31 bits would is undefined in C but in practice it would lead to shift wrapping. That would lead to an array overflow in nf_tables_addchain(): ops->hook = hook.type->hooks[ops->hooknum]; Fixes: fe19c04ca137 ("netfilter: nf_tables: remove nhooks field from struct nft_af_info") Signed-off-by: Dan Carpenter Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/netfilter/nf_tables_api.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 1af54119bafc..f272f9538c44 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -1496,7 +1496,7 @@ static int nft_chain_parse_hook(struct net *net, if (IS_ERR(type)) return PTR_ERR(type); } - if (!(type->hook_mask & (1 << hook->num))) + if (hook->num > NF_MAX_HOOKS || !(type->hook_mask & (1 << hook->num))) return -EOPNOTSUPP; if (type->type == NFT_CHAIN_T_NAT && -- GitLab