Re: [PATCH 5.10 104/157] mptcp: put subflow sock on connect error

[Greg Kroah-Hartman]

On Wed, Mar 24, 2021 at 02:02:06PM +0530, Naresh Kamboju wrote:
> On Mon, 22 Mar 2021 at 18:15, Greg Kroah-Hartman
> <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> >
> > From: Florian Westphal <fw@xxxxxxxxx>
> >
> > [ Upstream commit f07157792c633b528de5fc1dbe2e4ea54f8e09d4 ]
> >
> > mptcp_add_pending_subflow() performs a sock_hold() on the subflow,
> > then adds the subflow to the join list.
> >
> > Without a sock_put the subflow sk won't be freed in case connect() fails.
> >
> > unreferenced object 0xffff88810c03b100 (size 3000):
> > [..]
> >     sk_prot_alloc.isra.0+0x2f/0x110
> >     sk_alloc+0x5d/0xc20
> >     inet6_create+0x2b7/0xd30
> >     __sock_create+0x17f/0x410
> >     mptcp_subflow_create_socket+0xff/0x9c0
> >     __mptcp_subflow_connect+0x1da/0xaf0
> >     mptcp_pm_nl_work+0x6e0/0x1120
> >     mptcp_worker+0x508/0x9a0
> >
> > Fixes: 5b950ff4331ddda ("mptcp: link MPC subflow into msk only after accept")
> > Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
> > Signed-off-by: Mat Martineau <mathew.j.martineau@xxxxxxxxxxxxxxx>
> > Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> 
> I have reported the following warnings and kernel crash on 5.10.26-rc2 [1]
> The bisect reported that issue pointing out to this commit.
> 
> commit 460916534896e6d4f80a37152e0948db33376873
> mptcp: put subflow sock on connect error
> 
> This problem is specific to 5.10.26-rc2.

Thank you for tracking this down!