FAILED: patch "[PATCH] vrf: Fix use after free and double free in vrf_finish_output" failed to apply to 4.9-stable tree

FAILED: patch "[PATCH] vrf: Fix use after free and double free in vrf_finish_output" failed to apply to 4.9-stable tree

[gregkh]

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 82dd0d2a9a76fc8fa2b18d80b987d455728bf83a Mon Sep 17 00:00:00 2001
From: David Ahern <dsahern@gmail.com>
Date: Thu, 29 Mar 2018 12:49:52 -0700
Subject: [PATCH] vrf: Fix use after free and double free in vrf_finish_output

Miguel reported an skb use after free / double free in vrf_finish_output
when neigh_output returns an error. The vrf driver should return after
the call to neigh_output as it takes over the skb on error path as well.

Patch is a simplified version of Miguel's patch which was written for 4.9,
and updated to top of tree.

Fixes: 8f58336d3f78a ("net: Add ethernet header for pass through VRF device")
Signed-off-by: Miguel Fadon Perlines <mfadon@teldat.com>
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
index 139c61c8244a..ac40924fe437 100644
--- a/drivers/net/vrf.c
+++ b/drivers/net/vrf.c
@@ -578,12 +578,13 @@ static int vrf_finish_output(struct net *net, struct sock *sk, struct sk_buff *s
 	if (!IS_ERR(neigh)) {
 		sock_confirm_neigh(skb, neigh);
 		ret = neigh_output(neigh, skb);
+		rcu_read_unlock_bh();
+		return ret;
 	}
 
 	rcu_read_unlock_bh();
 err:
-	if (unlikely(ret < 0))
-		vrf_tx_error(skb->dev, skb);
+	vrf_tx_error(skb->dev, skb);
 	return ret;
 }
 

[PATCH] vrf: Fix use after free and double free in vrf_finish_output

[David Ahern]

[ upstream commit 82dd0d2a9a76fc8fa2b18d80b987d455728bf83a ]

Miguel reported an skb use after free / double free in vrf_finish_output
when neigh_output returns an error. The vrf driver should return after
the call to neigh_output as it takes over the skb on error path as well.

Patch is a simplified version of Miguel's patch which was written for 4.9,
and updated to top of tree.

Fixes: 8f58336d3f78a ("net: Add ethernet header for pass through VRF device")
Signed-off-by: Miguel Fadon Perlines <mfadon@teldat.com>
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[ backport to 4.4 and 4.9 dropped the sock_confirm_neigh and
  changed neigh_output to dst_neigh_output ]
---
note to stable: this patch applies to both 4.9 and 4.4 (the latter
has an offset but still applies cleanly

 drivers/net/vrf.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
index 346e48698555..42c9480acdc7 100644
--- a/drivers/net/vrf.c
+++ b/drivers/net/vrf.c
@@ -585,13 +585,15 @@ static int vrf_finish_output(struct net *net, struct sock *sk, struct sk_buff *s
 	neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
 	if (unlikely(!neigh))
 		neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);
-	if (!IS_ERR(neigh))
+	if (!IS_ERR(neigh)) {
 		ret = dst_neigh_output(dst, neigh, skb);
+		rcu_read_unlock_bh();
+		return ret;
+	}
 
 	rcu_read_unlock_bh();
 err:
-	if (unlikely(ret < 0))
-		vrf_tx_error(skb->dev, skb);
+	vrf_tx_error(skb->dev, skb);
 	return ret;
 }
 
-- 
2.11.0

Re: [PATCH] vrf: Fix use after free and double free in vrf_finish_output

[David Miller]

From: David Ahern <dsahern@gmail.com>
Date: Wed, 11 Apr 2018 08:10:03 -0700

> [ upstream commit 82dd0d2a9a76fc8fa2b18d80b987d455728bf83a ]
> 
> Miguel reported an skb use after free / double free in vrf_finish_output
> when neigh_output returns an error. The vrf driver should return after
> the call to neigh_output as it takes over the skb on error path as well.
> 
> Patch is a simplified version of Miguel's patch which was written for 4.9,
> and updated to top of tree.
> 
> Fixes: 8f58336d3f78a ("net: Add ethernet header for pass through VRF device")
> Signed-off-by: Miguel Fadon Perlines <mfadon@teldat.com>
> Signed-off-by: David Ahern <dsahern@gmail.com>
> Signed-off-by: David S. Miller <davem@davemloft.net>
> [ backport to 4.4 and 4.9 dropped the sock_confirm_neigh and
>   changed neigh_output to dst_neigh_output ]
> ---
> note to stable: this patch applies to both 4.9 and 4.4 (the latter
> has an offset but still applies cleanly

Stable folks, please queue this up.

Re: [PATCH] vrf: Fix use after free and double free in vrf_finish_output

[Greg KH]

On Wed, Apr 11, 2018 at 11:12:54AM -0400, David Miller wrote:
> From: David Ahern <dsahern@gmail.com>
> Date: Wed, 11 Apr 2018 08:10:03 -0700
> 
> > [ upstream commit 82dd0d2a9a76fc8fa2b18d80b987d455728bf83a ]
> > 
> > Miguel reported an skb use after free / double free in vrf_finish_output
> > when neigh_output returns an error. The vrf driver should return after
> > the call to neigh_output as it takes over the skb on error path as well.
> > 
> > Patch is a simplified version of Miguel's patch which was written for 4.9,
> > and updated to top of tree.
> > 
> > Fixes: 8f58336d3f78a ("net: Add ethernet header for pass through VRF device")
> > Signed-off-by: Miguel Fadon Perlines <mfadon@teldat.com>
> > Signed-off-by: David Ahern <dsahern@gmail.com>
> > Signed-off-by: David S. Miller <davem@davemloft.net>
> > [ backport to 4.4 and 4.9 dropped the sock_confirm_neigh and
> >   changed neigh_output to dst_neigh_output ]
> > ---
> > note to stable: this patch applies to both 4.9 and 4.4 (the latter
> > has an offset but still applies cleanly
> 
> Stable folks, please queue this up.

Now applied, thanks!

greg k-h