Fix skb_ensure_writable() size. Don't use nft_tcp_header_pointer() to
make it explicit that pointers point to the packet (not local buffer).
Fixes: 99d1712bc41c ("netfilter: exthdr: tcp option set support")
Fixes: 7890cbea66e7 ("netfilter: exthdr: add support for tcp option removal")
Signed-off-by: Xiao Liang <shaw.leon@xxxxxxxxx>
---
net/netfilter/nft_exthdr.c | 20 ++++++++------------
1 file changed, 8 insertions(+), 12 deletions(-)
diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c
index 7f856ceb3a66..a9844eefedeb 100644
--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -238,7 +238,12 @@ static void nft_exthdr_tcp_set_eval(const struct nft_expr *expr,
if (!tcph)
goto err;
+ if (skb_ensure_writable(pkt->skb, nft_thoff(pkt) + tcphdr_len))
+ goto err;
+
+ tcph = (struct tcphdr *)(pkt->skb->data + nft_thoff(pkt));
opt = (u8 *)tcph;
+
for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) {
union {
__be16 v16;
@@ -253,15 +258,6 @@ static void nft_exthdr_tcp_set_eval(const struct nft_expr *expr,
if (i + optl > tcphdr_len || priv->len + priv->offset > optl)
goto err;
- if (skb_ensure_writable(pkt->skb,
- nft_thoff(pkt) + i + priv->len))
- goto err;
-
- tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff,
- &tcphdr_len);
- if (!tcph)
- goto err;
-
offset = i + priv->offset;
switch (priv->len) {
@@ -325,9 +321,9 @@ static void nft_exthdr_tcp_strip_eval(const struct nft_expr *expr,
if (skb_ensure_writable(pkt->skb, nft_thoff(pkt) + tcphdr_len))
goto drop;
- opt = (u8 *)nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len);
- if (!opt)
- goto err;
+ tcph = (struct tcphdr *)(pkt->skb->data + nft_thoff(pkt));
+ opt = (u8 *)tcph;
+
for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) {
unsigned int j;
--
2.42.0
