[PATCH 4.19 046/243] virtchnl: Fix off by one error

[Greg Kroah-Hartman]

From: Alice Michael <alice.michael@xxxxxxxxx>

[ Upstream commit 843faff87af261bf55eda719a06087af0486a168 ]

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@xxxxxxxxx>
Tested-by: Andrew Bowers <andrewx.bowers@xxxxxxxxx>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 212b3822d1804..92d179fb6d59e 100644
--- a/include/linux/avf/virtchnl.h
+++ b/include/linux/avf/virtchnl.h
@@ -798,8 +798,8 @@ 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;
 		}
-- 
2.20.1