[Bridge] [PATCH] net: bridge: fix potential NULL pointer dereference

[Bridge] [PATCH] net: bridge: fix potential NULL pointer dereference

[Gustavo A. R. Silva]

Add NULL check before dereferencing pointer _p_ inside br_afspec().

Addresses-Coverity-ID: 1401872
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
---
 net/bridge/br_netlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 1e63ec4..ad85a9c 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -776,7 +776,7 @@ int br_setlink(struct net_device *dev, struct nlmsghdr *nlh, u16 flags)
 			goto out;
 	}
 
-	if (afspec) {
+	if (p && afspec) {
 		err = br_afspec((struct net_bridge *)netdev_priv(dev), p,
 				afspec, RTM_SETLINK);
 	}
-- 
2.5.0

[PATCH] net: bridge: fix potential NULL pointer dereference

[Gustavo A. R. Silva]

Add NULL check before dereferencing pointer _p_ inside br_afspec().

Addresses-Coverity-ID: 1401872
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
---
 net/bridge/br_netlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 1e63ec4..ad85a9c 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -776,7 +776,7 @@ int br_setlink(struct net_device *dev, struct nlmsghdr *nlh, u16 flags)
 			goto out;
 	}
 
-	if (afspec) {
+	if (p && afspec) {
 		err = br_afspec((struct net_bridge *)netdev_priv(dev), p,
 				afspec, RTM_SETLINK);
 	}
-- 
2.5.0

Re: [Bridge] [PATCH] net: bridge: fix potential NULL pointer dereference

[Nikolay Aleksandrov]

On 06/06/17 00:30, Gustavo A. R. Silva wrote:
> Add NULL check before dereferencing pointer _p_ inside br_afspec().
> 
> Addresses-Coverity-ID: 1401872
> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
> ---
>  net/bridge/br_netlink.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
> index 1e63ec4..ad85a9c 100644
> --- a/net/bridge/br_netlink.c
> +++ b/net/bridge/br_netlink.c
> @@ -776,7 +776,7 @@ int br_setlink(struct net_device *dev, struct nlmsghdr *nlh, u16 flags)
>  			goto out;
>  	}
>  
> -	if (afspec) {
> +	if (p && afspec) {
>  		err = br_afspec((struct net_bridge *)netdev_priv(dev), p,
>  				afspec, RTM_SETLINK);
>  	}
> 

While I see a possible issue with the new bridge tunnel code (+CC Roopa), this is 
the wrong fix because there are legitimate use cases where p is null and br_afspec
is called.
We need to change the p->flags check in br_afspec()'s IFLA_BRIDGE_VLAN_TUNNEL_INFO case
to check for a NULL p first.

Thanks for the report!

Re: [PATCH] net: bridge: fix potential NULL pointer dereference

[Nikolay Aleksandrov]

On 06/06/17 00:30, Gustavo A. R. Silva wrote:
> Add NULL check before dereferencing pointer _p_ inside br_afspec().
> 
> Addresses-Coverity-ID: 1401872
> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
> ---
>  net/bridge/br_netlink.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
> index 1e63ec4..ad85a9c 100644
> --- a/net/bridge/br_netlink.c
> +++ b/net/bridge/br_netlink.c
> @@ -776,7 +776,7 @@ int br_setlink(struct net_device *dev, struct nlmsghdr *nlh, u16 flags)
>  			goto out;
>  	}
>  
> -	if (afspec) {
> +	if (p && afspec) {
>  		err = br_afspec((struct net_bridge *)netdev_priv(dev), p,
>  				afspec, RTM_SETLINK);
>  	}
> 

While I see a possible issue with the new bridge tunnel code (+CC Roopa), this is 
the wrong fix because there are legitimate use cases where p is null and br_afspec
is called.
We need to change the p->flags check in br_afspec()'s IFLA_BRIDGE_VLAN_TUNNEL_INFO case
to check for a NULL p first.

Thanks for the report!

[Bridge] [PATCH net] net: bridge: fix a null pointer dereference in br_afspec

[Nikolay Aleksandrov]

We might call br_afspec() with p == NULL which is a valid use case if
the action is on the bridge device itself, but the bridge tunnel code
dereferences the p pointer without checking, so check if p is null
first.

Reported-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Fixes: efa5356b0d97 ("bridge: per vlan dst_metadata netlink support")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
---
 net/bridge/br_netlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 1e63ec466d7c..3bcda556971e 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -595,7 +595,7 @@ static int br_afspec(struct net_bridge *br,
 		err = 0;
 		switch (nla_type(attr)) {
 		case IFLA_BRIDGE_VLAN_TUNNEL_INFO:
-			if (!(p->flags & BR_VLAN_TUNNEL))
+			if (!p || !(p->flags & BR_VLAN_TUNNEL))
 				return -EINVAL;
 			err = br_parse_vlan_tunnel_info(attr, &tinfo_curr);
 			if (err)
-- 
2.1.4

[PATCH net] net: bridge: fix a null pointer dereference in br_afspec

[Nikolay Aleksandrov]

We might call br_afspec() with p == NULL which is a valid use case if
the action is on the bridge device itself, but the bridge tunnel code
dereferences the p pointer without checking, so check if p is null
first.

Reported-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Fixes: efa5356b0d97 ("bridge: per vlan dst_metadata netlink support")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
---
 net/bridge/br_netlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 1e63ec466d7c..3bcda556971e 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -595,7 +595,7 @@ static int br_afspec(struct net_bridge *br,
 		err = 0;
 		switch (nla_type(attr)) {
 		case IFLA_BRIDGE_VLAN_TUNNEL_INFO:
-			if (!(p->flags & BR_VLAN_TUNNEL))
+			if (!p || !(p->flags & BR_VLAN_TUNNEL))
 				return -EINVAL;
 			err = br_parse_vlan_tunnel_info(attr, &tinfo_curr);
 			if (err)
-- 
2.1.4

Re: [Bridge] [PATCH] net: bridge: fix potential NULL pointer dereference

[Gustavo A. R. Silva]

Hi Nikolay,

Quoting Nikolay Aleksandrov <nikolay@cumulusnetworks.com>:

> On 06/06/17 00:30, Gustavo A. R. Silva wrote:
>> Add NULL check before dereferencing pointer _p_ inside br_afspec().
>>
>> Addresses-Coverity-ID: 1401872
>> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
>> ---
>>  net/bridge/br_netlink.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
>> index 1e63ec4..ad85a9c 100644
>> --- a/net/bridge/br_netlink.c
>> +++ b/net/bridge/br_netlink.c
>> @@ -776,7 +776,7 @@ int br_setlink(struct net_device *dev, struct  
>> nlmsghdr *nlh, u16 flags)
>>  			goto out;
>>  	}
>>
>> -	if (afspec) {
>> +	if (p && afspec) {
>>  		err = br_afspec((struct net_bridge *)netdev_priv(dev), p,
>>  				afspec, RTM_SETLINK);
>>  	}
>>
>
> While I see a possible issue with the new bridge tunnel code (+CC  
> Roopa), this is
> the wrong fix because there are legitimate use cases where p is null  
> and br_afspec
> is called.
> We need to change the p->flags check in br_afspec()'s  
> IFLA_BRIDGE_VLAN_TUNNEL_INFO case
> to check for a NULL p first.
>

You're right. I got it.

> Thanks for the report!

Sure thing, glad to help.

Thank you!
--
Gustavo A. R. Silva

Re: [PATCH] net: bridge: fix potential NULL pointer dereference

[Gustavo A. R. Silva]

Hi Nikolay,

Quoting Nikolay Aleksandrov <nikolay@cumulusnetworks.com>:

> On 06/06/17 00:30, Gustavo A. R. Silva wrote:
>> Add NULL check before dereferencing pointer _p_ inside br_afspec().
>>
>> Addresses-Coverity-ID: 1401872
>> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
>> ---
>>  net/bridge/br_netlink.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
>> index 1e63ec4..ad85a9c 100644
>> --- a/net/bridge/br_netlink.c
>> +++ b/net/bridge/br_netlink.c
>> @@ -776,7 +776,7 @@ int br_setlink(struct net_device *dev, struct  
>> nlmsghdr *nlh, u16 flags)
>>  			goto out;
>>  	}
>>
>> -	if (afspec) {
>> +	if (p && afspec) {
>>  		err = br_afspec((struct net_bridge *)netdev_priv(dev), p,
>>  				afspec, RTM_SETLINK);
>>  	}
>>
>
> While I see a possible issue with the new bridge tunnel code (+CC  
> Roopa), this is
> the wrong fix because there are legitimate use cases where p is null  
> and br_afspec
> is called.
> We need to change the p->flags check in br_afspec()'s  
> IFLA_BRIDGE_VLAN_TUNNEL_INFO case
> to check for a NULL p first.
>

You're right. I got it.

> Thanks for the report!

Sure thing, glad to help.

Thank you!

Re: [Bridge] [PATCH net] net: bridge: fix a null pointer dereference in br_afspec

[Roopa Prabhu]

On Mon, Jun 5, 2017 at 3:26 PM, Nikolay Aleksandrov
<nikolay@cumulusnetworks.com> wrote:
> We might call br_afspec() with p == NULL which is a valid use case if
> the action is on the bridge device itself, but the bridge tunnel code
> dereferences the p pointer without checking, so check if p is null
> first.
>
> Reported-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
> Fixes: efa5356b0d97 ("bridge: per vlan dst_metadata netlink support")
> Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>

Acked-by: Roopa Prabhu <roopa@cumulusnetworks.com>

Thanks Nikolay.

Re: [PATCH net] net: bridge: fix a null pointer dereference in br_afspec

[Roopa Prabhu]

On Mon, Jun 5, 2017 at 3:26 PM, Nikolay Aleksandrov
<nikolay@cumulusnetworks.com> wrote:
> We might call br_afspec() with p == NULL which is a valid use case if
> the action is on the bridge device itself, but the bridge tunnel code
> dereferences the p pointer without checking, so check if p is null
> first.
>
> Reported-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
> Fixes: efa5356b0d97 ("bridge: per vlan dst_metadata netlink support")
> Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>

Acked-by: Roopa Prabhu <roopa@cumulusnetworks.com>

Thanks Nikolay.

Re: [Bridge] [PATCH net] net: bridge: fix a null pointer dereference in br_afspec

[David Miller]

From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Date: Tue,  6 Jun 2017 01:26:24 +0300

> We might call br_afspec() with p == NULL which is a valid use case if
> the action is on the bridge device itself, but the bridge tunnel code
> dereferences the p pointer without checking, so check if p is null
> first.
> 
> Reported-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
> Fixes: efa5356b0d97 ("bridge: per vlan dst_metadata netlink support")
> Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>

Applied and queued up for -stable, thanks Nikolay.

Re: [PATCH net] net: bridge: fix a null pointer dereference in br_afspec

[David Miller]

From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Date: Tue,  6 Jun 2017 01:26:24 +0300

> We might call br_afspec() with p == NULL which is a valid use case if
> the action is on the bridge device itself, but the bridge tunnel code
> dereferences the p pointer without checking, so check if p is null
> first.
> 
> Reported-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
> Fixes: efa5356b0d97 ("bridge: per vlan dst_metadata netlink support")
> Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>

Applied and queued up for -stable, thanks Nikolay.