From: Cong Wang <xiyou.wangcong@xxxxxxxxx>
[ Upstream commit 0e4940928c26527ce8f97237fef4c8a91cd34207 ]
After pskb_may_pull() we should always refetch the header
pointers from the skb->data in case it got reallocated.
In gre_parse_header(), the erspan header is still fetched
from the 'options' pointer which is fetched before
pskb_may_pull().
Found this during code review of a KMSAN bug report.
Fixes: cb73ee40b1b3 ("net: ip_gre: use erspan key field for tunnel lookup")
Cc: Lorenzo Bianconi <lorenzo.bianconi@xxxxxxxxxx>
Signed-off-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Acked-by: Lorenzo Bianconi <lorenzo.bianconi@xxxxxxxxxx>
Acked-by: William Tu <u9012063@xxxxxxxxx>
Reviewed-by: Simon Horman <simon.horman@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/gre_demux.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/ipv4/gre_demux.c
+++ b/net/ipv4/gre_demux.c
@@ -127,7 +127,7 @@ int gre_parse_header(struct sk_buff *skb
if (!pskb_may_pull(skb, nhs + hdr_len + sizeof(*ershdr)))
return -EINVAL;
- ershdr = (struct erspan_base_hdr *)options;
+ ershdr = (struct erspan_base_hdr *)(skb->data + nhs + hdr_len);
tpi->key = cpu_to_be32(get_session_id(ershdr));
}
