On Fri, Jun 1, 2018 at 4:18 AM Prashant Bhole
<bhole_prashant...@lab.ntt.co.jp> wrote:
>
> In rtnl_newlink(), NULL check is performed on m_ops however member of
> ops is accessed. Fixed by accessing member of m_ops instead of ops.
>
> [ 345.432629] BUG: KASAN: null-ptr-deref in rtnl_newlink+0x400/0x1110
> [ 345.432629] Read of size 4 at addr 0000000000000088 by task ip/986
> [ 345.432629]
> [ 345.432629] CPU: 1 PID: 986 Comm: ip Not tainted 4.17.0-rc6+ #9
> [ 345.432629] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> 1.10.2-1ubuntu1 04/01/2014
> [ 345.432629] Call Trace:
> [ 345.432629] dump_stack+0xc6/0x150
> [ 345.432629] ? dump_stack_print_info.cold.0+0x1b/0x1b
> [ 345.432629] ? kasan_report+0xb4/0x410
> [ 345.432629] kasan_report.cold.4+0x8f/0x91
> [ 345.432629] ? rtnl_newlink+0x400/0x1110
> [ 345.432629] rtnl_newlink+0x400/0x1110
> [...]
>
> Fixes: ccf8dbcd062a ("rtnetlink: Remove VLA usage")
> Signed-off-by: Prashant Bhole <bhole_prashant...@lab.ntt.co.jp>
> ---
> net/core/rtnetlink.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index 8ca49a0e13fb..9a1ba2015ad8 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> @@ -2936,7 +2936,7 @@ static int rtnl_newlink(struct sk_buff *skb, struct
> nlmsghdr *nlh,
> }
>
> if (m_ops) {
> - if (ops->slave_maxtype > RTNL_SLAVE_MAX_TYPE)
> + if (m_ops->slave_maxtype > RTNL_SLAVE_MAX_TYPE)
> return -EINVAL;
Oh nice
CC Kees Cook.
