On Thu, 26 Nov 2020 16:23:08 +0100 Matthieu Baerts wrote:
> On 26/11/2020 15:17, Paolo Abeni wrote:
> > If an msk listener receives an MPJ carrying an invalid token, it
> > will zero the request socket msk entry. That should later
> > cause fallback and subflow reset - as per RFC - at
> > subflow_syn_recv_sock() time due to failing hmac validation.
> >
> > Since commit 4cf8b7e48a09 ("subflow: introduce and use
> > mptcp_can_accept_new_subflow()"), we unconditionally dereference
> > - in mptcp_can_accept_new_subflow - the subflow request msk
> > before performing hmac validation. In the above scenario we
> > hit a NULL ptr dereference.
> >
> > Address the issue doing the hmac validation earlier.
> >
> > Fixes: 4cf8b7e48a09 ("subflow: introduce and use
> > mptcp_can_accept_new_subflow()")
> > Tested-by: Davide Caratti <[email protected]>
> > Signed-off-by: Paolo Abeni <[email protected]>
>
> Good catch! Thank you for the patch!
>
> Reviewed-by: Matthieu Baerts <[email protected]>
Applied, thanks!
