Patchwork [net-next-2.6] tunnels: missing rcu_assign_pointer()

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Submitter Eric Dumazet
Date Sept. 9, 2010, 3:33 p.m.
Message ID <1284046423.2589.188.camel@edumazet-laptop>
Download mbox | patch
Permalink /patch/64309/
State Accepted
Delegated to: David Miller
Headers show

Comments

Eric Dumazet - Sept. 9, 2010, 3:33 p.m.
xfrm4_tunnel_register() & xfrm6_tunnel_register() should
use rcu_assign_pointer() to make sure previous writes
(to handler->next) are committed to memory before chain
insertion.

deregister functions dont need a particular barrier.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
---
No risk of crash, because handler->next is NULL before register()
call, but a possibility of packet being dropped.

 net/ipv4/tunnel4.c |    2 +-
 net/ipv6/tunnel6.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)



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David Miller - Sept. 9, 2010, 10:02 p.m.
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 09 Sep 2010 17:33:43 +0200

> xfrm4_tunnel_register() & xfrm6_tunnel_register() should
> use rcu_assign_pointer() to make sure previous writes
> (to handler->next) are committed to memory before chain
> insertion.
> 
> deregister functions dont need a particular barrier.
> 
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

Applied, thanks Eric.
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Patch

diff --git a/net/ipv4/tunnel4.c b/net/ipv4/tunnel4.c
index df59d16..9a17bd2 100644
--- a/net/ipv4/tunnel4.c
+++ b/net/ipv4/tunnel4.c
@@ -39,7 +39,7 @@  int xfrm4_tunnel_register(struct xfrm_tunnel *handler, unsigned short family)
 	}
 
 	handler->next = *pprev;
-	*pprev = handler;
+	rcu_assign_pointer(*pprev, handler);
 
 	ret = 0;
 
diff --git a/net/ipv6/tunnel6.c b/net/ipv6/tunnel6.c
index 3177fe0..d986472 100644
--- a/net/ipv6/tunnel6.c
+++ b/net/ipv6/tunnel6.c
@@ -51,7 +51,7 @@  int xfrm6_tunnel_register(struct xfrm6_tunnel *handler, unsigned short family)
 	}
 
 	handler->next = *pprev;
-	*pprev = handler;
+	rcu_assign_pointer(*pprev, handler);
 
 	ret = 0;