[PATCH net] hv_netvsc: Reset the RSC count if NVSP_STAT_FAIL in netvsc_receive()

[Andrea Parri (Microsoft)]

Commit 44144185951a0f ("hv_netvsc: Add validation for untrusted Hyper-V
values") added validation to rndis_filter_receive_data() (and
rndis_filter_receive()) which introduced NVSP_STAT_FAIL-scenarios where
the count is not updated/reset.  Fix this omission, and prevent similar
scenarios from occurring in the future.

Reported-by: Juan Vazquez <juvazq@xxxxxxxxxxxxx>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Fixes: 44144185951a0f ("hv_netvsc: Add validation for untrusted Hyper-V values")
---
 drivers/net/hyperv/netvsc.c       | 5 ++++-
 drivers/net/hyperv/rndis_filter.c | 2 --
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 2350342b961ff..13bd48a75db76 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -1262,8 +1262,11 @@ static int netvsc_receive(struct net_device *ndev,
 		ret = rndis_filter_receive(ndev, net_device,
 					   nvchan, data, buflen);
 
-		if (unlikely(ret != NVSP_STAT_SUCCESS))
+		if (unlikely(ret != NVSP_STAT_SUCCESS)) {
+			/* Drop incomplete packet */
+			nvchan->rsc.cnt = 0;
 			status = NVSP_STAT_FAIL;
+		}
 	}
 
 	enq_receive_complete(ndev, net_device, q_idx,
diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 598713c0d5a87..3aab2b867fc0d 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -509,8 +509,6 @@ static int rndis_filter_receive_data(struct net_device *ndev,
 	return ret;
 
 drop:
-	/* Drop incomplete packet */
-	nvchan->rsc.cnt = 0;
 	return NVSP_STAT_FAIL;
 }
 
-- 
2.25.1