diff mbox series

usb: gadget: rndis: Avoid dereference before NULL check

Message ID 20220908175615.5095-1-jilin@nvidia.com
State New
Headers show
Series usb: gadget: rndis: Avoid dereference before NULL check | expand

Commit Message

Jim Lin Sept. 8, 2022, 5:56 p.m. UTC 
NULL check is performed after params->dev is dereferenced in
dev_get_stats.
Fixed by adding a NULL check before dereferencing params->dev and
removing subsequent NULL checks for it.

Signed-off-by: Aniruddha TVS Rao <anrao@nvidia.com>
Signed-off-by: Jim Lin <jilin@nvidia.com>
---
 drivers/usb/gadget/function/rndis.c | 37 ++++++++++++-----------------
 1 file changed, 15 insertions(+), 22 deletions(-)

Comments

Sergei Shtylyov Sept. 22, 2022, 9 p.m. UTC | #1 
Hello!

On 9/9/22 8:38 AM, Greg KH wrote:

>> NULL check is performed after params->dev is dereferenced in
>> dev_get_stats.
> 
> I do not understand this statement.
> 
>> Fixed by adding a NULL check before dereferencing params->dev and
>> removing subsequent NULL checks for it.
>>
>> Signed-off-by: Aniruddha TVS Rao <anrao@nvidia.com>
>> Signed-off-by: Jim Lin <jilin@nvidia.com>
>> ---
>>  drivers/usb/gadget/function/rndis.c | 37 ++++++++++++-----------------
>>  1 file changed, 15 insertions(+), 22 deletions(-)
>>
>> diff --git a/drivers/usb/gadget/function/rndis.c b/drivers/usb/gadget/function/rndis.c
>> index 64de9f1b874c..d2f18f34c8e5 100644
>> --- a/drivers/usb/gadget/function/rndis.c
>> +++ b/drivers/usb/gadget/function/rndis.c
>> @@ -198,6 +198,9 @@ static int gen_ndis_query_resp(struct rndis_params *params, u32 OID, u8 *buf,
>>  	outbuf = (__le32 *)&resp[1];
>>  	resp->InformationBufferOffset = cpu_to_le32(16);
>>  
>> +	if (!params->dev)
>> +		return -ENODEV;
>> +
> 
> As Sergey points out, this check is useless and the ones below should
> also be removed.

   Would you accept this patch modulo the above check then? If not,
I'll just resolve the corresponding SVACE checker as "won't fix" here. :-)

> But, why make this check at all, how did you trigger a problem with the
> current code?

   There's no problem, just the redundant NULL checks...

> Are you using this driver?  If so, why?  It is totally broken (as per
> the specification) and we really really need to just delete it from the
> tree to prevent anyone else from ever using it.

   Well, delete it then... :-)

> thanks,
> 
> greg k-h

MBR, Sergey
diff mbox series

Patch

diff --git a/drivers/usb/gadget/function/rndis.c b/drivers/usb/gadget/function/rndis.c
index 64de9f1b874c..d2f18f34c8e5 100644
--- a/drivers/usb/gadget/function/rndis.c
+++ b/drivers/usb/gadget/function/rndis.c
@@ -198,6 +198,9 @@  static int gen_ndis_query_resp(struct rndis_params *params, u32 OID, u8 *buf,
 	outbuf = (__le32 *)&resp[1];
 	resp->InformationBufferOffset = cpu_to_le32(16);
 
+	if (!params->dev)
+		return -ENODEV;
+
 	net = params->dev;
 	stats = dev_get_stats(net, &temp);
 
@@ -246,10 +249,8 @@  static int gen_ndis_query_resp(struct rndis_params *params, u32 OID, u8 *buf,
 	/* mandatory */
 	case RNDIS_OID_GEN_MAXIMUM_FRAME_SIZE:
 		pr_debug("%s: RNDIS_OID_GEN_MAXIMUM_FRAME_SIZE\n", __func__);
-		if (params->dev) {
-			*outbuf = cpu_to_le32(params->dev->mtu);
-			retval = 0;
-		}
+		*outbuf = cpu_to_le32(params->dev->mtu);
+		retval = 0;
 		break;
 
 	/* mandatory */
@@ -266,19 +267,15 @@  static int gen_ndis_query_resp(struct rndis_params *params, u32 OID, u8 *buf,
 	/* mandatory */
 	case RNDIS_OID_GEN_TRANSMIT_BLOCK_SIZE:
 		pr_debug("%s: RNDIS_OID_GEN_TRANSMIT_BLOCK_SIZE\n", __func__);
-		if (params->dev) {
-			*outbuf = cpu_to_le32(params->dev->mtu);
-			retval = 0;
-		}
+		*outbuf = cpu_to_le32(params->dev->mtu);
+		retval = 0;
 		break;
 
 	/* mandatory */
 	case RNDIS_OID_GEN_RECEIVE_BLOCK_SIZE:
 		pr_debug("%s: RNDIS_OID_GEN_RECEIVE_BLOCK_SIZE\n", __func__);
-		if (params->dev) {
-			*outbuf = cpu_to_le32(params->dev->mtu);
-			retval = 0;
-		}
+		*outbuf = cpu_to_le32(params->dev->mtu);
+		retval = 0;
 		break;
 
 	/* mandatory */
@@ -405,21 +402,17 @@  static int gen_ndis_query_resp(struct rndis_params *params, u32 OID, u8 *buf,
 	/* mandatory */
 	case RNDIS_OID_802_3_PERMANENT_ADDRESS:
 		pr_debug("%s: RNDIS_OID_802_3_PERMANENT_ADDRESS\n", __func__);
-		if (params->dev) {
-			length = ETH_ALEN;
-			memcpy(outbuf, params->host_mac, length);
-			retval = 0;
-		}
+		length = ETH_ALEN;
+		memcpy(outbuf, params->host_mac, length);
+		retval = 0;
 		break;
 
 	/* mandatory */
 	case RNDIS_OID_802_3_CURRENT_ADDRESS:
 		pr_debug("%s: RNDIS_OID_802_3_CURRENT_ADDRESS\n", __func__);
-		if (params->dev) {
-			length = ETH_ALEN;
-			memcpy(outbuf, params->host_mac, length);
-			retval = 0;
-		}
+		length = ETH_ALEN;
+		memcpy(outbuf, params->host_mac, length);
+		retval = 0;
 		break;
 
 	/* mandatory */