Re: [PATCH] e1000: avoid null pointer dereference on invalid stat type

2017-09-22 Thread Colin Ian King 
On 22/09/17 12:50, Dan Carpenter wrote:
> On Thu, Sep 21, 2017 at 11:01:58PM +0100, Colin King wrote:
>> @@ -1837,12 +1838,13 @@ static void e1000_get_ethtool_stats(struct 
>> net_device *netdev,
>>  p = (char *)adapter + stat->stat_offset;
>>  break;
>>  default:
>> +p = NULL;
>>  WARN_ONCE(1, "Invalid E1000 stat type: %u index %d\n",
>>stat->type, i);
>>  break;
>>  }
>>  
>> -if (stat->sizeof_stat == sizeof(u64))
>> +if (p && stat->sizeof_stat == sizeof(u64))
>>  data[i] = *(u64 *)p;
>>  else
>>  data[i] = *(u32 *)p;
>
> 
> The else side will still crash.
> 
> regards,
> dan carpenter
> 
Thanks, stupid me. I'll fix that up.

Re: [PATCH] e1000: avoid null pointer dereference on invalid stat type

2017-09-22 Thread Dan Carpenter 
On Thu, Sep 21, 2017 at 11:01:58PM +0100, Colin King wrote:
> @@ -1837,12 +1838,13 @@ static void e1000_get_ethtool_stats(struct net_device 
> *netdev,
>   p = (char *)adapter + stat->stat_offset;
>   break;
>   default:
> + p = NULL;
>   WARN_ONCE(1, "Invalid E1000 stat type: %u index %d\n",
> stat->type, i);
>   break;
>   }
>  
> - if (stat->sizeof_stat == sizeof(u64))
> + if (p && stat->sizeof_stat == sizeof(u64))
>   data[i] = *(u64 *)p;
>   else
>   data[i] = *(u32 *)p;
   

The else side will still crash.

regards,
dan carpenter

[PATCH] e1000: avoid null pointer dereference on invalid stat type

2017-09-21 Thread Colin King 
From: Colin Ian King 

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 nullify pointer p if a stat type is
invalid and only setting data if p is not null.

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

Signed-off-by: Colin Ian King 
---
 drivers/net/ethernet/intel/e1000/e1000_ethtool.c | 6 --
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000/e1000_ethtool.c 
b/drivers/net/ethernet/intel/e1000/e1000_ethtool.c
index ec8aa4562cc9..2ef6f08b580b 100644
--- a/drivers/net/ethernet/intel/e1000/e1000_ethtool.c
+++ b/drivers/net/ethernet/intel/e1000/e1000_ethtool.c
@@ -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++) {
+   char *p;
+
switch (stat->type) {
case NETDEV_STATS:
p = (char *)netdev + stat->stat_offset;
@@ -1837,12 +1838,13 @@ static void e1000_get_ethtool_stats(struct net_device 
*netdev,
p = (char *)adapter + stat->stat_offset;
break;
default:
+   p = NULL;
WARN_ONCE(1, "Invalid E1000 stat type: %u index %d\n",
  stat->type, i);
break;
}
 
-   if (stat->sizeof_stat == sizeof(u64))
+   if (p && stat->sizeof_stat == sizeof(u64))
data[i] = *(u64 *)p;
else
data[i] = *(u32 *)p;
-- 
2.14.1