[SRU,Xenial,1/1] s390/qeth: fix L3 next-hop in xmit qeth hdr

From: Julian Wiedmann <jwi@linux.vnet.ibm.com>

BugLink: http://bugs.launchpad.net/bugs/1750813

On L3, the qeth_hdr struct needs to be filled with the next-hop
IP address.
The current code accesses rtable->rt_gateway without checking that
rtable is a valid address. The accidental access to a lowcore area
results in a random next-hop address in the qeth_hdr.
rtable (or more precisely, skb_dst(skb)) can be NULL in rare cases
(for instance together with AF_PACKET sockets).
This patch adds the missing NULL-ptr checks.

Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Fixes: 87e7597b5a3 qeth: Move away from using neighbour entries in qeth_l3_fill_header()
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit ec2c6726322f0d270bab477e4904bf9496f70ee5)
Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
---
 drivers/s390/net/qeth_l3_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

On 2018-03-01 14:01:53 , Joseph Salisbury wrote:
> From: Julian Wiedmann <jwi@linux.vnet.ibm.com>
> 
> BugLink: http://bugs.launchpad.net/bugs/1750813
> 
> On L3, the qeth_hdr struct needs to be filled with the next-hop
> IP address.
> The current code accesses rtable->rt_gateway without checking that
> rtable is a valid address. The accidental access to a lowcore area
> results in a random next-hop address in the qeth_hdr.
> rtable (or more precisely, skb_dst(skb)) can be NULL in rare cases
> (for instance together with AF_PACKET sockets).
> This patch adds the missing NULL-ptr checks.
> 
> Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
> Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
> Fixes: 87e7597b5a3 qeth: Move away from using neighbour entries in qeth_l3_fill_header()
> Signed-off-by: David S. Miller <davem@davemloft.net>
> (cherry picked from commit ec2c6726322f0d270bab477e4904bf9496f70ee5)
> Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
> ---
>  drivers/s390/net/qeth_l3_main.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
> index bf3c1b2..84774c3 100644
> --- a/drivers/s390/net/qeth_l3_main.c
> +++ b/drivers/s390/net/qeth_l3_main.c
> @@ -2727,7 +2727,7 @@ static void qeth_l3_fill_header(struct qeth_card *card, struct qeth_hdr *hdr,
>  		struct rtable *rt = (struct rtable *) dst;
>  		__be32 *pkey = &ip_hdr(skb)->daddr;
>  
> -		if (rt->rt_gateway)
> +		if (rt && rt->rt_gateway)
>  			pkey = &rt->rt_gateway;
>  
>  		/* IPv4 */
> @@ -2738,7 +2738,7 @@ static void qeth_l3_fill_header(struct qeth_card *card, struct qeth_hdr *hdr,
>  		struct rt6_info *rt = (struct rt6_info *) dst;
>  		struct in6_addr *pkey = &ipv6_hdr(skb)->daddr;
>  
> -		if (!ipv6_addr_any(&rt->rt6i_gateway))
> +		if (rt && !ipv6_addr_any(&rt->rt6i_gateway))
>  			pkey = &rt->rt6i_gateway;
>  
>  		/* IPv6 */
> -- 
> 2.7.4
> 
> 

Acked-by: Khalid Elmously <khalid.elmously@canonical.com>

On 03/01/18 20:01, Joseph Salisbury wrote:
> From: Julian Wiedmann <jwi@linux.vnet.ibm.com>
> 
> BugLink: http://bugs.launchpad.net/bugs/1750813
> 
> On L3, the qeth_hdr struct needs to be filled with the next-hop
> IP address.
> The current code accesses rtable->rt_gateway without checking that
> rtable is a valid address. The accidental access to a lowcore area
> results in a random next-hop address in the qeth_hdr.
> rtable (or more precisely, skb_dst(skb)) can be NULL in rare cases
> (for instance together with AF_PACKET sockets).
> This patch adds the missing NULL-ptr checks.
> 
> Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
> Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
> Fixes: 87e7597b5a3 qeth: Move away from using neighbour entries in qeth_l3_fill_header()
> Signed-off-by: David S. Miller <davem@davemloft.net>
> (cherry picked from commit ec2c6726322f0d270bab477e4904bf9496f70ee5)
> Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
> ---
>  drivers/s390/net/qeth_l3_main.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
> index bf3c1b2..84774c3 100644
> --- a/drivers/s390/net/qeth_l3_main.c
> +++ b/drivers/s390/net/qeth_l3_main.c
> @@ -2727,7 +2727,7 @@ static void qeth_l3_fill_header(struct qeth_card *card, struct qeth_hdr *hdr,
>  		struct rtable *rt = (struct rtable *) dst;
>  		__be32 *pkey = &ip_hdr(skb)->daddr;
>  
> -		if (rt->rt_gateway)
> +		if (rt && rt->rt_gateway)
>  			pkey = &rt->rt_gateway;
>  
>  		/* IPv4 */
> @@ -2738,7 +2738,7 @@ static void qeth_l3_fill_header(struct qeth_card *card, struct qeth_hdr *hdr,
>  		struct rt6_info *rt = (struct rt6_info *) dst;
>  		struct in6_addr *pkey = &ipv6_hdr(skb)->daddr;
>  
> -		if (!ipv6_addr_any(&rt->rt6i_gateway))
> +		if (rt && !ipv6_addr_any(&rt->rt6i_gateway))
>  			pkey = &rt->rt6i_gateway;
>  
>  		/* IPv6 */
> 

Scope limited to an architecture specific driver, tested by the vendor.

Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>