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e1000: avoid null pointer dereference on invalid stat type
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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>
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Colin Ian King authored and Jeff Kirsher committed Oct 26, 2017
1 parent 44c445c commit 5983587
Showing 1 changed file with 4 additions and 5 deletions.
9 changes: 4 additions & 5 deletions drivers/net/ethernet/intel/e1000/e1000_ethtool.c
Original file line number Diff line number Diff line change
Expand Up @@ -1824,11 +1824,12 @@ 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;
Expand All @@ -1839,15 +1840,13 @@ 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); */
}
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