netdev - Re: [PATCH net-next v2] ipv6: Error when route does not have any valid nexthops

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Message-ID: <33fa3e48-bd8b-abe5-ee9e-32ecaeca65b0@gmail.com>
Date:   Thu, 20 Jun 2019 06:57:23 -0600
From:   David Ahern <dsahern@...il.com>
To:     Ido Schimmel <idosch@...sch.org>, netdev@...r.kernel.org
Cc:     davem@...emloft.net, mlxsw@...lanox.com,
        Ido Schimmel <idosch@...lanox.com>
Subject: Re: [PATCH net-next v2] ipv6: Error when route does not have any
 valid nexthops

On 6/20/19 3:10 AM, Ido Schimmel wrote:
> From: Ido Schimmel <idosch@...lanox.com>
> 
> When user space sends invalid information in RTA_MULTIPATH, the nexthop
> list in ip6_route_multipath_add() is empty and 'rt_notif' is set to
> NULL.
> 
> The code that emits the in-kernel notifications does not check for this
> condition, which results in a NULL pointer dereference [1].
> 
> Fix this by bailing earlier in the function if the parsed nexthop list
> is empty. This is consistent with the corresponding IPv4 code.
> 
> v2:
> * Check if parsed nexthop list is empty and bail with extack set
> 
...
> 
> Reported-by: syzbot+382566d339d52cd1a204@...kaller.appspotmail.com
> Fixes: ebee3cad835f ("ipv6: Add IPv6 multipath notifications for add / replace")
> Signed-off-by: Ido Schimmel <idosch@...lanox.com>
> ---
>  net/ipv6/route.c | 6 ++++++
>  1 file changed, 6 insertions(+)

Reviewed-by: David Ahern <dsahern@...il.com>