linux-kernel - [PATCH 3.16 036/212] IB/ipoib: rtnl_unlock can not come after free

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Date:   Thu, 01 Jun 2017 16:43:15 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Leon Romanovsky" <leon@...nel.org>,
        "Or Gerlitz" <ogerlitz@...lanox.com>,
        "Feras Daoud" <ferasda@...lanox.com>,
        "Doug Ledford" <dledford@...hat.com>,
        "Erez Shitrit" <erezsh@...lanox.com>,
        "Yuval Shaia" <yuval.shaia@...cle.com>
Subject: [PATCH 3.16 036/212] IB/ipoib: rtnl_unlock can not come after
 free_netdev

3.16.44-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Feras Daoud <ferasda@...lanox.com>

commit 89a3987ab7a923c047c6dec008e60ad6f41fac22 upstream.

The ipoib_vlan_add function calls rtnl_unlock after free_netdev,
rtnl_unlock not only releases the lock, but also calls netdev_run_todo.
The latter function browses the net_todo_list array and completes the
unregistration of all its net_device instances. If we call free_netdev
before rtnl_unlock, then netdev_run_todo call over the freed device causes
panic.
To fix, move rtnl_unlock call before free_netdev call.

Fixes: 9baa0b036410 ("IB/ipoib: Add rtnl_link_ops support")
Cc: Or Gerlitz <ogerlitz@...lanox.com>
Signed-off-by: Feras Daoud <ferasda@...lanox.com>
Signed-off-by: Erez Shitrit <erezsh@...lanox.com>
Reviewed-by: Yuval Shaia <yuval.shaia@...cle.com>
Signed-off-by: Leon Romanovsky <leon@...nel.org>
Signed-off-by: Doug Ledford <dledford@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/infiniband/ulp/ipoib/ipoib_vlan.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
@@ -168,11 +168,11 @@ int ipoib_vlan_add(struct net_device *pd
 out:
 	up_write(&ppriv->vlan_rwsem);
 
+	rtnl_unlock();
+
 	if (result)
 		free_netdev(priv->dev);
 
-	rtnl_unlock();
-
 	return result;
 }