[SRU][J:linux-azure][PATCH 1/1] net: hv_netvsc: reject RSS hash key programming without RX indirection table

[Vinicius Peixoto]

From: Aditya Garg <gargaditya at linux.microsoft.com>

BugLink: https://bugs.launchpad.net/bugs/2142703

RSS configuration requires a valid RX indirection table. When the device
reports a single receive queue, rndis_filter_device_add() does not
allocate an indirection table, accepting RSS hash key updates in this
state leads to a hang.

Fix this by gating netvsc_set_rxfh() on ndc->rx_table_sz and return
-EOPNOTSUPP when the table is absent. This aligns set_rxfh with the device
capabilities and prevents incorrect behavior.

Fixes: 962f3fee83a4 ("netvsc: add ethtool ops to get/set RSS key")
Signed-off-by: Aditya Garg <gargaditya at linux.microsoft.com>
Reviewed-by: Dipayaan Roy <dipayanroy at linux.microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz at microsoft.com>
Link: https://patch.msgid.link/1768212093-1594-1-git-send-email-gargaditya@linux.microsoft.com
Signed-off-by: Jakub Kicinski <kuba at kernel.org>
(cherry picked from commit d23564955811da493f34412d7de60fa268c8cb50)
Signed-off-by: Vinicius Peixoto <vinicius.peixoto at canonical.com>
---
 drivers/net/hyperv/netvsc_drv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index be64bdf3baa8..506c95d1477e 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -1795,6 +1795,9 @@ static int netvsc_set_rxfh(struct net_device *dev, const u32 *indir,
 	if (hfunc != ETH_RSS_HASH_NO_CHANGE && hfunc != ETH_RSS_HASH_TOP)
 		return -EOPNOTSUPP;
 
+	if (!ndc->rx_table_sz)
+		return -EOPNOTSUPP;
+
 	rndis_dev = ndev->extension;
 	if (indir) {
 		for (i = 0; i < ITAB_NUM; i++)
-- 
2.51.0