From: Cong Wang xiyou.wangcong@gmail.com
[ 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@redhat.com Signed-off-by: Cong Wang xiyou.wangcong@gmail.com Acked-by: Lorenzo Bianconi lorenzo.bianconi@redhat.com Acked-by: William Tu u9012063@gmail.com Reviewed-by: Simon Horman simon.horman@netronome.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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)); }