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netfilter: nft_meta: fix wrong value dereference in nft_meta_set_eval 

commit 97a0549b15 upstream.

In the nft_meta_set_eval, nftrace value is dereferenced as u32 from sreg.
But correct type is u8. so that sometimes incorrect value is dereferenced.

Steps to reproduce:

   %nft add table ip filter
   %nft add chain ip filter input { type filter hook input priority 4\; }
   %nft add rule ip filter input nftrace set 0
   %nft monitor

Sometimes, we can see trace messages.

   trace id 16767227 ip filter input packet: iif "enp2s0"
   ether saddr xx:xx:xx:xx:xx:xx ether daddr xx:xx:xx:xx:xx:xx
   ip saddr 192.168.0.1 ip daddr 255.255.255.255 ip dscp cs0
   ip ecn not-ect ip
   trace id 16767227 ip filter input rule nftrace set 0 (verdict continue)
   trace id 16767227 ip filter input verdict continue
   trace id 16767227 ip filter input

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
Taehee Yoo 2018-05-17 22:49:49 +09:00 committed by Greg Kroah-Hartman
parent 2b93cb2861
commit 491b1a866e
1 changed files with 8 additions and 6 deletions
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14
net/netfilter/nft_meta.c
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@ -229,7 +229,7 @@ void nft_meta_set_eval(const struct nft_expr *expr,
struct sk_buff *skb = pkt->skb;
u32 *sreg = &regs->data[meta->sreg];
u32 value = *sreg;
u8 pkt_type;
u8 value8;
switch (meta->key) {
case NFT_META_MARK:
@ -239,15 +239,17 @@ void nft_meta_set_eval(const struct nft_expr *expr,
skb->priority = value;
break;
case NFT_META_PKTTYPE:
pkt_type = nft_reg_load8(sreg);
value8 = nft_reg_load8(sreg);
if (skb->pkt_type != pkt_type &&
skb_pkt_type_ok(pkt_type) &&
if (skb->pkt_type != value8 &&
skb_pkt_type_ok(value8) &&
skb_pkt_type_ok(skb->pkt_type))
skb->pkt_type = pkt_type;
skb->pkt_type = value8;
break;
case NFT_META_NFTRACE:
skb->nf_trace = !!value;
value8 = nft_reg_load8(sreg);
skb->nf_trace = !!value8;
break;
default:
WARN_ON(1);