netdev - Re: [PATCH] ipcomp: double free at ipcomp

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Message-ID: <20100216052430.GA27643@gondor.apana.org.au>
Date:	Tue, 16 Feb 2010 13:24:30 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Alexey Dobriyan <adobriyan@...il.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH] ipcomp: double free at ipcomp_destroy()

On Mon, Feb 15, 2010 at 07:28:10PM +0200, Alexey Dobriyan wrote:
>
> OK, it survives beating here.

Thanks a lot for testing! I'll do the clean-up you suggested in
another patch.  Let's get this fixed first.

ipcomp: Avoid duplicate calls to ipcomp_destroy

When ipcomp_tunnel_attach fails we will call ipcomp_destroy twice.
This may lead to double-frees on certain structures.

As there is no reason to explicitly call ipcomp_destroy, this patch
removes it from ipcomp*.c and lets the standard xfrm_state destruction
take place.

This is based on the discovery and patch by Alexey Dobriyan.

Tested-by: Alexey Dobriyan <adobriyan@...il.com>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

diff --git a/net/ipv4/ipcomp.c b/net/ipv4/ipcomp.c
index 38fbf04..544ce08 100644
--- a/net/ipv4/ipcomp.c
+++ b/net/ipv4/ipcomp.c
@@ -124,16 +124,12 @@ static int ipcomp4_init_state(struct xfrm_state *x)
 	if (x->props.mode == XFRM_MODE_TUNNEL) {
 		err = ipcomp_tunnel_attach(x);
 		if (err)
-			goto error_tunnel;
+			goto out;
 	}
 
 	err = 0;
 out:
 	return err;
-
-error_tunnel:
-	ipcomp_destroy(x);
-	goto out;
 }
 
 static const struct xfrm_type ipcomp_type = {
diff --git a/net/ipv6/ipcomp6.c b/net/ipv6/ipcomp6.c
index 2f2a5ca..002e6ee 100644
--- a/net/ipv6/ipcomp6.c
+++ b/net/ipv6/ipcomp6.c
@@ -154,16 +154,12 @@ static int ipcomp6_init_state(struct xfrm_state *x)
 	if (x->props.mode == XFRM_MODE_TUNNEL) {
 		err = ipcomp6_tunnel_attach(x);
 		if (err)
-			goto error_tunnel;
+			goto out;
 	}
 
 	err = 0;
 out:
 	return err;
-error_tunnel:
-	ipcomp_destroy(x);
-
-	goto out;
 }
 
 static const struct xfrm_type ipcomp6_type =

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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