rule_locs is allocated in ethtool_get_rxnfc and the size is determined by
rule_cnt from user space. So rule_cnt needs to be check before using
rule_locs to avoid OOB writing or NULL pointer dereference.

Fixes: c5d511c49587 ("net: bcmasp: Add support for wake on net filters")
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
---
 drivers/net/ethernet/broadcom/asp2/bcmasp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/broadcom/asp2/bcmasp.c b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
index d63d321f3e7b..4df2ca871af8 100644
--- a/drivers/net/ethernet/broadcom/asp2/bcmasp.c
+++ b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
@@ -535,6 +535,9 @@ void bcmasp_netfilt_get_all_active(struct bcmasp_intf *intf, u32 *rule_locs,
 	int j = 0, i;
 
 	for (i = 0; i < NUM_NET_FILTERS; i++) {
+		if (j == *rule_cnt)
+			break;
+
 		if (!priv->net_filters[i].claimed ||
 		    priv->net_filters[i].port != intf->port)
 			continue;
-- 
2.34.1

On Wed, 2023-09-06 at 17:21 +0800, Hangyu Hua wrote:
> rule_locs is allocated in ethtool_get_rxnfc and the size is determined by
> rule_cnt from user space. So rule_cnt needs to be check before using
> rule_locs to avoid OOB writing or NULL pointer dereference.
> 
> Fixes: c5d511c49587 ("net: bcmasp: Add support for wake on net filters")
> Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
> ---
>  drivers/net/ethernet/broadcom/asp2/bcmasp.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/net/ethernet/broadcom/asp2/bcmasp.c b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
> index d63d321f3e7b..4df2ca871af8 100644
> --- a/drivers/net/ethernet/broadcom/asp2/bcmasp.c
> +++ b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
> @@ -535,6 +535,9 @@ void bcmasp_netfilt_get_all_active(struct bcmasp_intf *intf, u32 *rule_locs,
>  	int j = 0, i;
>  
>  	for (i = 0; i < NUM_NET_FILTERS; i++) {
> +		if (j == *rule_cnt)
> +			break;

Side note: it's a bit unfortunate/confusing that the drivers can
arbitrary return  -EMSGSIZE or silently truncate the list. I think it
would be clearer if we could stick to single behavior - and I'll vote
for -EMSGSIZE.

Cheers,

Paolo

On 7/9/2023 17:44, Paolo Abeni wrote:
> On Wed, 2023-09-06 at 17:21 +0800, Hangyu Hua wrote:
>> rule_locs is allocated in ethtool_get_rxnfc and the size is determined by
>> rule_cnt from user space. So rule_cnt needs to be check before using
>> rule_locs to avoid OOB writing or NULL pointer dereference.
>>
>> Fixes: c5d511c49587 ("net: bcmasp: Add support for wake on net filters")
>> Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
>> ---
>>   drivers/net/ethernet/broadcom/asp2/bcmasp.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/broadcom/asp2/bcmasp.c b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
>> index d63d321f3e7b..4df2ca871af8 100644
>> --- a/drivers/net/ethernet/broadcom/asp2/bcmasp.c
>> +++ b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
>> @@ -535,6 +535,9 @@ void bcmasp_netfilt_get_all_active(struct bcmasp_intf *intf, u32 *rule_locs,
>>   	int j = 0, i;
>>   
>>   	for (i = 0; i < NUM_NET_FILTERS; i++) {
>> +		if (j == *rule_cnt)
>> +			break;
> 
> Side note: it's a bit unfortunate/confusing that the drivers can
> arbitrary return  -EMSGSIZE or silently truncate the list. I think it
> would be clearer if we could stick to single behavior - and I'll vote
> for -EMSGSIZE.

I see. I used break directly here beacause this function is defined as
void. But since you mentioned this I will fix this out.

Thanks,
Hangyu

> 
> Cheers,
> 
> Paolo
>

On 9/6/23 2:21 AM, Hangyu Hua wrote:
> rule_locs is allocated in ethtool_get_rxnfc and the size is determined by
> rule_cnt from user space. So rule_cnt needs to be check before using
> rule_locs to avoid OOB writing or NULL pointer dereference.
> 
> Fixes: c5d511c49587 ("net: bcmasp: Add support for wake on net filters")
> Signed-off-by: Hangyu Hua <hbh25y@gmail.com>

Reviewed-by: Justin Chen <justin.chen@broadcom.com>

> ---
>   drivers/net/ethernet/broadcom/asp2/bcmasp.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/net/ethernet/broadcom/asp2/bcmasp.c b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
> index d63d321f3e7b..4df2ca871af8 100644
> --- a/drivers/net/ethernet/broadcom/asp2/bcmasp.c
> +++ b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
> @@ -535,6 +535,9 @@ void bcmasp_netfilt_get_all_active(struct bcmasp_intf *intf, u32 *rule_locs,
>   	int j = 0, i;
>   
>   	for (i = 0; i < NUM_NET_FILTERS; i++) {
> +		if (j == *rule_cnt)
> +			break;
> +
>   		if (!priv->net_filters[i].claimed ||
>   		    priv->net_filters[i].port != intf->port)
>   			continue;