linux-kernel - [PATCH 5.1 18/98] geneve: Dont assume linear buffers in error handler

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Date:   Thu, 20 Jun 2019 19:56:45 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Guillaume Nault <gnault@...hat.com>,
        Stefano Brivio <sbrivio@...hat.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.1 18/98] geneve: Dont assume linear buffers in error handler

From: Stefano Brivio <sbrivio@...hat.com>

[ Upstream commit eccc73a6b2cb6c04bfbc40a0769f3c428dfba232 ]

In commit a07966447f39 ("geneve: ICMP error lookup handler") I wrongly
assumed buffers from icmp_socket_deliver() would be linear. This is not
the case: icmp_socket_deliver() only guarantees we have 8 bytes of linear
data.

Eric fixed this same issue for fou and fou6 in commits 26fc181e6cac
("fou, fou6: do not assume linear skbs") and 5355ed6388e2 ("fou, fou6:
avoid uninit-value in gue_err() and gue6_err()").

Use pskb_may_pull() instead of checking skb->len, and take into account
the fact we later access the GENEVE header with udp_hdr(), so we also
need to sum skb_transport_header() here.

Reported-by: Guillaume Nault <gnault@...hat.com>
Fixes: a07966447f39 ("geneve: ICMP error lookup handler")
Signed-off-by: Stefano Brivio <sbrivio@...hat.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/geneve.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -396,7 +396,7 @@ static int geneve_udp_encap_err_lookup(s
 	u8 zero_vni[3] = { 0 };
 	u8 *vni = zero_vni;

-	if (skb->len < GENEVE_BASE_HLEN)
+	if (!pskb_may_pull(skb, skb_transport_offset(skb) + GENEVE_BASE_HLEN))
 		return -EINVAL;

 	geneveh = geneve_hdr(skb);