current/SOURCES/netfilter-nft_payload-incorrect-arithmetics-when-fetching-vlan-header-bits.patch

From 696e1a48b1a1b01edad542a1ef293665864a4dd0 Mon Sep 17 00:00:00 2001
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Wed, 11 Jan 2023 17:07:33 +0100
Subject: netfilter: nft_payload: incorrect arithmetics when fetching VLAN header bits

From: Pablo Neira Ayuso <pablo@netfilter.org>

commit 696e1a48b1a1b01edad542a1ef293665864a4dd0 upstream.

If the offset + length goes over the ethernet + vlan header, then the
length is adjusted to copy the bytes that are within the boundaries of
the vlan_ethhdr scratchpad area. The remaining bytes beyond ethernet +
vlan header are copied directly from the skbuff data area.

Fix incorrect arithmetic operator: subtract, not add, the size of the
vlan header in case of double-tagged packets to adjust the length
accordingly to address CVE-2023-0179.

Reported-by: Davide Ornaghi <d.ornaghi97@gmail.com>
Fixes: f6ae9f120dad ("netfilter: nft_payload: add C-VLAN support")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/netfilter/nft_payload.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/netfilter/nft_payload.c
+++ b/net/netfilter/nft_payload.c
@@ -62,7 +62,7 @@ nft_payload_copy_vlan(u32 *d, const stru
                        return false;
 
                if (offset + len > VLAN_ETH_HLEN + vlan_hlen)
-                       ethlen -= offset + len - VLAN_ETH_HLEN + vlan_hlen;
+                       ethlen -= offset + len - VLAN_ETH_HLEN - vlan_hlen;
 
                memcpy(dst_u8, vlanh + offset - vlan_hlen, ethlen);
 
1	From 696e1a48b1a1b01edad542a1ef293665864a4dd0 Mon Sep 17 00:00:00 2001
2	From: Pablo Neira Ayuso <pablo@netfilter.org>
3	Date: Wed, 11 Jan 2023 17:07:33 +0100
4	Subject: netfilter: nft_payload: incorrect arithmetics when fetching VLAN header bits
5
6	From: Pablo Neira Ayuso <pablo@netfilter.org>
7
8	commit 696e1a48b1a1b01edad542a1ef293665864a4dd0 upstream.
9
10	If the offset + length goes over the ethernet + vlan header, then the
11	length is adjusted to copy the bytes that are within the boundaries of
12	the vlan_ethhdr scratchpad area. The remaining bytes beyond ethernet +
13	vlan header are copied directly from the skbuff data area.
14
15	Fix incorrect arithmetic operator: subtract, not add, the size of the
16	vlan header in case of double-tagged packets to adjust the length
17	accordingly to address CVE-2023-0179.
18
19	Reported-by: Davide Ornaghi <d.ornaghi97@gmail.com>
20	Fixes: f6ae9f120dad ("netfilter: nft_payload: add C-VLAN support")
21	Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
22	Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
23	---
24	net/netfilter/nft_payload.c \| 2 +-
25	1 file changed, 1 insertion(+), 1 deletion(-)
26
27	--- a/net/netfilter/nft_payload.c
28	+++ b/net/netfilter/nft_payload.c
29	@@ -62,7 +62,7 @@ nft_payload_copy_vlan(u32 *d, const stru
30	return false;
31
32	if (offset + len > VLAN_ETH_HLEN + vlan_hlen)
33	- ethlen -= offset + len - VLAN_ETH_HLEN + vlan_hlen;
34	+ ethlen -= offset + len - VLAN_ETH_HLEN - vlan_hlen;
35
36	memcpy(dst_u8, vlanh + offset - vlan_hlen, ethlen);
37