[PATCH net] net/smc: fix ethernet interface refcounting

[PATCH net] net/smc: fix ethernet interface refcounting

[Karsten Graul]

From: Ursula Braun <ubraun@linux.ibm.com>

If a pnet table entry is to be added mentioning a valid ethernet
interface, but an invalid infiniband or ISM device, the dev_put()
operation for the ethernet interface is called twice, resulting
in a negative refcount for the ethernet interface, which disables
removal of such a network interface.

This patch removes one of the dev_put() calls.

Fixes: 890a2cb4a966 ("net/smc: rework pnet table")
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
---
 net/smc/smc_pnet.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/net/smc/smc_pnet.c b/net/smc/smc_pnet.c
index 2920b006f65c..571e6d84da3b 100644
--- a/net/smc/smc_pnet.c
+++ b/net/smc/smc_pnet.c
@@ -376,8 +376,6 @@ static int smc_pnet_fill_entry(struct net *net,
 	return 0;
 
 error:
-	if (pnetelem->ndev)
-		dev_put(pnetelem->ndev);
 	return rc;
 }
 
-- 
2.17.1

Re: [PATCH net] net/smc: fix ethernet interface refcounting

[David Miller]

From: Karsten Graul <kgraul@linux.ibm.com>
Date: Wed,  6 Nov 2019 10:49:57 +0100

> From: Ursula Braun <ubraun@linux.ibm.com>
> 
> If a pnet table entry is to be added mentioning a valid ethernet
> interface, but an invalid infiniband or ISM device, the dev_put()
> operation for the ethernet interface is called twice, resulting
> in a negative refcount for the ethernet interface, which disables
> removal of such a network interface.
> 
> This patch removes one of the dev_put() calls.
> 
> Fixes: 890a2cb4a966 ("net/smc: rework pnet table")
> Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
> Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>

Applied and queued up for -stable, thanks.