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netfilter: nf_tables: prevent shift wrap in nft_chain_parse_hook()

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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: fe19c04ca1 ("netfilter: nf_tables: remove nhooks field from struct nft_af_info")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Dan Carpenter 2019-04-06 08:26:52 +03:00 committed by Pablo Neira Ayuso
parent 3c79107631
commit 33d1c01817
1 changed files with 1 additions and 1 deletions
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2
net/netfilter/nf_tables_api.c
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@ -1545,7 +1545,7 @@ 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 &&