[PATCH 4.9 23/83] e1000: avoid null pointer dereference on invalid stat type

Greg Kroah-Hartman
2018-11-19T16:53:15Z

[ Upstream commit 5983587c8c5ef00d6886477544ad67d495bc5479 ]

Currently if the stat type is invalid then data[i] is being set
either by dereferencing a null pointer p, or it is reading from
an incorrect previous location if we had a valid stat type
previously. Fix this by skipping over the read of p on an invalid
stat type.

Detected by CoverityScan, CID#113385 ("Explicit null dereferenced")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/intel/e1000/e1000_ethtool.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000/e1000_ethtool.c b/drivers/net/ethernet/intel/e1000/e1000_ethtool.c
index e84574b1eae7..2a81f6d72140 100644
--- a/drivers/net/ethernet/intel/e1000/e1000_ethtool.c
+++ b/drivers/net/ethernet/intel/e1000/e1000_ethtool.c
@@ -1826,11 +1826,12 @@ static void e1000_get_ethtool_stats(struct net_device *netdev,
{
struct e1000_adapter *adapter = netdev_priv(netdev);
int i;
- char *p = NULL;
const struct e1000_stats *stat = e1000_gstrings_stats;

e1000_update_stats(adapter);
- for (i = 0; i < E1000_GLOBAL_STATS_LEN; i++) {
+ for (i = 0; i < E1000_GLOBAL_STATS_LEN; i++, stat++) {
+ char *p;
+
switch (stat->type) {
case NETDEV_STATS:
p = (char *)netdev + stat->stat_offset;
@@ -1841,15 +1842,13 @@ static void e1000_get_ethtool_stats(struct net_device *netdev,
default:
WARN_ONCE(1, "Invalid E1000 stat type: %u index %d\n",
stat->type, i);
- break;
+ continue;
}

if (stat->sizeof_stat == sizeof(u64))
data[i] = *(u64 *)p;
else
data[i] = *(u32 *)p;
-
- stat++;
}
/* BUG_ON(i != E1000_STATS_LEN); */
}
--
2.17.1