The result of nlmsg_find_attr() 'br_spec' is dereferenced in
nla_for_each_nested(), but it can take NULL value in nla_find() function,
which will result in an error.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 51616018dd1b ("i40e: Add support for getlink, setlink ndo ops")
Signed-off-by: Natalia Petrova <n.petrova@fintech.ru>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
---
v3: Fixed mailing list.
v2: The remark about the error code by Simon Horman <simon.horman@corigine.com> 
was taken into account; return value -ENOENT was changed to -EINVAL.
 drivers/net/ethernet/intel/i40e/i40e_main.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 53d0083e35da..4626d2a1af91 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -13167,6 +13167,8 @@ static int i40e_ndo_bridge_setlink(struct net_device *dev,
 	}
 
 	br_spec = nlmsg_find_attr(nlh, sizeof(struct ifinfomsg), IFLA_AF_SPEC);
+	if (!br_spec)
+		return -EINVAL;
 
 	nla_for_each_nested(attr, br_spec, rem) {
 		__u16 mode;
-- 
2.34.1

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf Of
> Natalia Petrova
> Sent: Wednesday, February 1, 2023 2:36 PM
> To: Brandeburg, Jesse <jesse.brandeburg@intel.com>
> Cc: lvc-project@linuxtesting.org; intel-wired-lan@lists.osuosl.org; Natalia
> Petrova <n.petrova@fintech.ru>; linux-kernel@vger.kernel.org; Eric
> Dumazet <edumazet@google.com>; Nguyen, Anthony L
> <anthony.l.nguyen@intel.com>; netdev@vger.kernel.org; Jakub Kicinski
> <kuba@kernel.org>; Paolo Abeni <pabeni@redhat.com>; David S. Miller
> <davem@davemloft.net>
> Subject: [Intel-wired-lan] [PATCH v3] i40e: Add checking for null for
> nlmsg_find_attr()
> 
> The result of nlmsg_find_attr() 'br_spec' is dereferenced in
> nla_for_each_nested(), but it can take NULL value in nla_find() function,
> which will result in an error.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: 51616018dd1b ("i40e: Add support for getlink, setlink ndo ops")
> Signed-off-by: Natalia Petrova <n.petrova@fintech.ru>
> Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
> ---
> v3: Fixed mailing list.
> v2: The remark about the error code by Simon Horman
> <simon.horman@corigine.com> was taken into account; return value -
> ENOENT was changed to -EINVAL.
>  drivers/net/ethernet/intel/i40e/i40e_main.c | 2 ++
>  1 file changed, 2 insertions(+)
> 

Tested-by: Gurucharan G <gurucharanx.g@intel.com> (A Contingent worker at Intel)

On 2/1/2023 1:06 AM, Natalia Petrova wrote:
> The result of nlmsg_find_attr() 'br_spec' is dereferenced in
> nla_for_each_nested(), but it can take NULL value in nla_find() function,
> which will result in an error.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: 51616018dd1b ("i40e: Add support for getlink, setlink ndo ops")
> Signed-off-by: Natalia Petrova <n.petrova@fintech.ru>
> Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
> ---

Thanks for the patch. I've applied it, however, for the future if you 
could specify the target tree. Simon mentioned it in v2, but his example 
omitted the tree.

i.e.
[PATCH v3 net] i40e: Add checking for null for nlmsg_find_attr()

Thanks,
Tony

> v3: Fixed mailing list.
> v2: The remark about the error code by Simon Horman <simon.horman@corigine.com>
> was taken into account; return value -ENOENT was changed to -EINVAL.
>   drivers/net/ethernet/intel/i40e/i40e_main.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
> index 53d0083e35da..4626d2a1af91 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> @@ -13167,6 +13167,8 @@ static int i40e_ndo_bridge_setlink(struct net_device *dev,
>   	}
>   
>   	br_spec = nlmsg_find_attr(nlh, sizeof(struct ifinfomsg), IFLA_AF_SPEC);
> +	if (!br_spec)
> +		return -EINVAL;
>   
>   	nla_for_each_nested(attr, br_spec, rem) {
>   		__u16 mode;