[PATCH 5.6 050/118] net: mvpp2: prevent buffer overflow in mvpp22_rss_ctx()

[Greg Kroah-Hartman]

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

[ Upstream commit 39bd16df7c31bb8cf5dfd0c88e42abd5ae10029d ]

The "rss_context" variable comes from the user via  ethtool_get_rxfh().
It can be any u32 value except zero.  Eventually it gets passed to
mvpp22_rss_ctx() and if it is over MVPP22_N_RSS_TABLES (8) then it
results in an array overflow.

Fixes: 895586d5dc32 ("net: mvpp2: cls: Use RSS contexts to handle RSS tables")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -4325,6 +4325,8 @@ static int mvpp2_ethtool_get_rxfh_contex
 
 	if (!mvpp22_rss_is_supported())
 		return -EOPNOTSUPP;
+	if (rss_context >= MVPP22_N_RSS_TABLES)
+		return -EINVAL;
 
 	if (hfunc)
 		*hfunc = ETH_RSS_HASH_CRC32;