Re: [PATCH 1/4] RDMA/cm: Fix memory leak in cm_add/remove_one

Leon Romanovsky
2019-09-25T06:16:24Z

On Mon, Sep 16, 2019 at 06:45:48PM +0000, Jason Gunthorpe wrote:
> On Mon, Sep 16, 2019 at 10:11:51AM +0300, Leon Romanovsky wrote:
> > From: Jack Morgenstein <jackm@dev.mellanox.co.il>
> >
> > In the process of moving the debug counters sysfs entries, the commit
> > mentioned below eliminated the cm_infiniband sysfs directory.
> >
> > This sysfs directory was tied to the cm_port object allocated in procedure
> > cm_add_one().
> >
> > Before the commit below, this cm_port object was freed via a call to
> > kobject_put(port->kobj) in procedure cm_remove_port_fs().
> >
> > Since port no longer uses its kobj, kobject_put(port->kobj) was eliminated.
> > This, however, meant that kfree was never called for the cm_port buffers.
> >
> > Fix this by adding explicit kfree(port) calls to functions cm_add_one()
> > and cm_remove_one().
> >
> > Note: the kfree call in the first chunk below (in the cm_add_one error
> > flow) fixes an old, undetected memory leak.
> >
> > Fixes: c87e65cfb97c ("RDMA/cm: Move debug counters to be under relevant IB device")
> > Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
> > Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
> > drivers/infiniband/core/cm.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
> > index da10e6ccb43c..5920c0085d35 100644
> > +++ b/drivers/infiniband/core/cm.c
> > @@ -4399,6 +4399,7 @@ static void cm_add_one(struct ib_device *ib_device)
> > error1:
> > port_modify.set_port_cap_mask = 0;
> > port_modify.clr_port_cap_mask = IB_PORT_CM_SUP;
> > + kfree(port);
> > while (--i) {
> > if (!rdma_cap_ib_cm(ib_device, i))
> > continue;
> > @@ -4407,6 +4408,7 @@ static void cm_add_one(struct ib_device *ib_device)
> > ib_modify_port(ib_device, port->port_num, 0, &port_modify);
> > ib_unregister_mad_agent(port->mad_agent);
> > cm_remove_port_fs(port);
> > + kfree(port);
> > }
> > free:
> > kfree(cm_dev);
> > @@ -4460,6 +4462,7 @@ static void cm_remove_one(struct ib_device *ib_device, void *client_data)
> > spin_unlock_irq(&cm.state_lock);
> > ib_unregister_mad_agent(cur_mad_agent);
> > cm_remove_port_fs(port);
> > + kfree(port);
> > }
>
> This whole thing is looking pretty goofy now, and I suspect there are
> more error unwind bugs here.
>
> How about this instead:
>
> From e8dad20c7b69436e63b18f16cd9457ea27da5bc1 Mon Sep 17 00:00:00 2001
> From: Jack Morgenstein <jackm@dev.mellanox.co.il>
> Date: Mon, 16 Sep 2019 10:11:51 +0300
> Subject: [PATCH] RDMA/cm: Fix memory leak in cm_add/remove_one
>
> In the process of moving the debug counters sysfs entries, the commit
> mentioned below eliminated the cm_infiniband sysfs directory, and created
> some missing cases where the port pointers were not being freed as the
> kobject_put was also eliminated.
>
> Rework this to not allocate port pointers and consolidate all the error
> unwind into one sequence.
>
> This also fixes unlikely racey bugs where error-unwind after unregistering
> the MAD handler would miss flushing the WQ and other clean up that is
> necessary once concurrency starts.
>
> Fixes: c87e65cfb97c ("RDMA/cm: Move debug counters to be under relevant IB device")
> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
> ---
> drivers/infiniband/core/cm.c | 187 ++++++++++++++++++-----------------
> 1 file changed, 94 insertions(+), 93 deletions(-)

The proposed patch doesn't pass sanity check and unfortunately, I don't
have time now to debug it.

$ ./rping -V -S 256 -C 100 -p 19663 -P -a 192.168.0.1 -s &
$ ./rping -V -S 256 -C 100 -p 19663 -a 192.168.0.1 -c -I 192.168.0.1
rdma_connect: Invalid argument
connect error -1
<hang>

Thanks