netdev - [net-next 11/14] virtchnl: Fix off by one error

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Message-Id: <20181114231032.4013-12-jeffrey.t.kirsher@intel.com>
Date:   Wed, 14 Nov 2018 15:10:29 -0800
From:   Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:     davem@...emloft.net
Cc:     Alice Michael <alice.michael@...el.com>, netdev@...r.kernel.org,
        nhorman@...hat.com, sassmann@...hat.com,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Subject: [net-next 11/14] virtchnl: Fix off by one error

From: Alice Michael <alice.michael@...el.com>

When calculating the valid length for a VIRTCHNL_OP_ENABLE_CHANNELS
message, we accidentally allowed messages with one extra
virtchnl_channel_info structure on the end. This happened due
to an off by one error, because we forgot that valid_len already
accounted for one virtchnl_channel_info structure, so we need to
subtract one from the num_tc value.

Signed-off-by: Alice Michael <alice.michael@...el.com>
Tested-by: Andrew Bowers <andrewx.bowers@...el.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
---
 include/linux/avf/virtchnl.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/avf/virtchnl.h b/include/linux/avf/virtchnl.h
index 3130dec40b93..7605b5919c3a 100644
--- a/include/linux/avf/virtchnl.h
+++ b/include/linux/avf/virtchnl.h
@@ -819,8 +819,8 @@ virtchnl_vc_validate_vf_msg(struct virtchnl_version_info *ver, u32 v_opcode,
 		if (msglen >= valid_len) {
 			struct virtchnl_tc_info *vti =
 				(struct virtchnl_tc_info *)msg;
-			valid_len += vti->num_tc *
-				sizeof(struct virtchnl_channel_info);
+			valid_len += (vti->num_tc - 1) *
+				     sizeof(struct virtchnl_channel_info);
 			if (vti->num_tc == 0)
 				err_msg_format = true;
 		}
-- 
2.19.1