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Subject[PATCH 5.4 172/388] RDMA/cm: Remove a race freeing timewait_info
Date
From: Jason Gunthorpe <jgg@mellanox.com>

[ Upstream commit bede86a39d9dc3387ac00dcb8e1ac221676b2f25 ]

When creating a cm_id during REQ the id immediately becomes visible to the
other MAD handlers, and shortly after the state is moved to IB_CM_REQ_RCVD

This allows cm_rej_handler() to run concurrently and free the work:

CPU 0 CPU1
cm_req_handler()
ib_create_cm_id()
cm_match_req()
id_priv->state = IB_CM_REQ_RCVD
cm_rej_handler()
cm_acquire_id()
spin_lock(&id_priv->lock)
switch (id_priv->state)
case IB_CM_REQ_RCVD:
cm_reset_to_idle()
kfree(id_priv->timewait_info);
goto destroy
destroy:
kfree(id_priv->timewait_info);
id_priv->timewait_info = NULL

Causing a double free or worse.

Do not free the timewait_info without also holding the
id_priv->lock. Simplify this entire flow by making the free unconditional
during cm_destroy_id() and removing the confusing special case error
unwind during creation of the timewait_info.

This also fixes a leak of the timewait if cm_destroy_id() is called in
IB_CM_ESTABLISHED with an XRC TGT QP. The state machine will be left in
ESTABLISHED while it needed to transition through IB_CM_TIMEWAIT to
release the timewait pointer.

Also fix a leak of the timewait_info if the caller mis-uses the API and
does ib_send_cm_reqs().

Fixes: a977049dacde ("[PATCH] IB: Add the kernel CM implementation")
Link: https://lore.kernel.org/r/20200310092545.251365-4-leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/infiniband/core/cm.c | 25 +++++++++++++++----------
1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
index 09af96ec41dd6..c1d6a068f50fe 100644
--- a/drivers/infiniband/core/cm.c
+++ b/drivers/infiniband/core/cm.c
@@ -1092,14 +1092,22 @@ retest:
break;
}

- spin_lock_irq(&cm.lock);
+ spin_lock_irq(&cm_id_priv->lock);
+ spin_lock(&cm.lock);
+ /* Required for cleanup paths related cm_req_handler() */
+ if (cm_id_priv->timewait_info) {
+ cm_cleanup_timewait(cm_id_priv->timewait_info);
+ kfree(cm_id_priv->timewait_info);
+ cm_id_priv->timewait_info = NULL;
+ }
if (!list_empty(&cm_id_priv->altr_list) &&
(!cm_id_priv->altr_send_port_not_ready))
list_del(&cm_id_priv->altr_list);
if (!list_empty(&cm_id_priv->prim_list) &&
(!cm_id_priv->prim_send_port_not_ready))
list_del(&cm_id_priv->prim_list);
- spin_unlock_irq(&cm.lock);
+ spin_unlock(&cm.lock);
+ spin_unlock_irq(&cm_id_priv->lock);

cm_free_id(cm_id->local_id);
cm_deref_id(cm_id_priv);
@@ -1416,7 +1424,7 @@ int ib_send_cm_req(struct ib_cm_id *cm_id,
/* Verify that we're not in timewait. */
cm_id_priv = container_of(cm_id, struct cm_id_private, id);
spin_lock_irqsave(&cm_id_priv->lock, flags);
- if (cm_id->state != IB_CM_IDLE) {
+ if (cm_id->state != IB_CM_IDLE || WARN_ON(cm_id_priv->timewait_info)) {
spin_unlock_irqrestore(&cm_id_priv->lock, flags);
ret = -EINVAL;
goto out;
@@ -1434,12 +1442,12 @@ int ib_send_cm_req(struct ib_cm_id *cm_id,
param->ppath_sgid_attr, &cm_id_priv->av,
cm_id_priv);
if (ret)
- goto error1;
+ goto out;
if (param->alternate_path) {
ret = cm_init_av_by_path(param->alternate_path, NULL,
&cm_id_priv->alt_av, cm_id_priv);
if (ret)
- goto error1;
+ goto out;
}
cm_id->service_id = param->service_id;
cm_id->service_mask = ~cpu_to_be64(0);
@@ -1457,7 +1465,7 @@ int ib_send_cm_req(struct ib_cm_id *cm_id,

ret = cm_alloc_msg(cm_id_priv, &cm_id_priv->msg);
if (ret)
- goto error1;
+ goto out;

req_msg = (struct cm_req_msg *) cm_id_priv->msg->mad;
cm_format_req(req_msg, cm_id_priv, param);
@@ -1480,7 +1488,6 @@ int ib_send_cm_req(struct ib_cm_id *cm_id,
return 0;

error2: cm_free_msg(cm_id_priv->msg);
-error1: kfree(cm_id_priv->timewait_info);
out: return ret;
}
EXPORT_SYMBOL(ib_send_cm_req);
@@ -1965,7 +1972,7 @@ static int cm_req_handler(struct cm_work *work)
pr_debug("%s: local_id %d, no listen_cm_id_priv\n", __func__,
be32_to_cpu(cm_id->local_id));
ret = -EINVAL;
- goto free_timeinfo;
+ goto destroy;
}

cm_id_priv->id.cm_handler = listen_cm_id_priv->id.cm_handler;
@@ -2050,8 +2057,6 @@ static int cm_req_handler(struct cm_work *work)
rejected:
atomic_dec(&cm_id_priv->refcount);
cm_deref_id(listen_cm_id_priv);
-free_timeinfo:
- kfree(cm_id_priv->timewait_info);
destroy:
ib_destroy_cm_id(cm_id);
return ret;
--
2.25.1


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