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Date: Thu, 26 Nov 2020 16:23:08 +0100 From: Matthieu Baerts <matthieu.baerts@...sares.net> To: Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org Cc: Jakub Kicinski <kuba@...nel.org>, mptcp@...ts.01.org Subject: Re: [PATCH net] mptcp: fix NULL ptr dereference on bad MPJ Hi Paolo, 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 <dcaratti@...hat.com> > Signed-off-by: Paolo Abeni <pabeni@...hat.com> Good catch! Thank you for the patch! Reviewed-by: Matthieu Baerts <matthieu.baerts@...sares.net> Cheers, Matt -- Tessares | Belgium | Hybrid Access Solutions www.tessares.net
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