linux-kernel - Re: kernel BUG at net/key/af

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Message-ID: <20171110031406.GA22823@gondor.apana.org.au>
Date:   Fri, 10 Nov 2017 14:14:06 +1100
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     syzbot 
        <bot+413384116f7f7dab7903d54c53fc4af6a4441965@...kaller.appspotmail.com>,
        David Miller <davem@...emloft.net>,
        LKML <linux-kernel@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        syzkaller-bugs@...glegroups.com
Subject: Re: kernel BUG at net/key/af_key.c:LINE!

On Fri, Nov 10, 2017 at 01:30:38PM +1100, Herbert Xu wrote:
> 
> I found the problem.  This crap is coming from clone_policy.  Now
> let me where this code came from.

---8<---
Subject: xfrm: Copy policy family in clone_policy

The syzbot found an ancient bug in the IPsec code.  When we cloned
a socket policy (for example, for a child TCP socket derived from a
listening socket), we did not copy the family field.  This results
in a live policy with a zero family field.  This triggers a BUG_ON
check in the af_key code when the cloned policy is retrieved.

This patch fixes it by copying the family field over.

Reported-by: syzbot <syzkaller@...glegroups.com>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 8cafb3c..c238959 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1306,6 +1306,7 @@ static struct xfrm_policy *clone_policy(const struct xfrm_policy *old, int dir)
 		newp->xfrm_nr = old->xfrm_nr;
 		newp->index = old->index;
 		newp->type = old->type;
+		newp->family = old->family;
 		memcpy(newp->xfrm_vec, old->xfrm_vec,
 		       newp->xfrm_nr*sizeof(struct xfrm_tmpl));
 		spin_lock_bh(&net->xfrm.xfrm_policy_lock);
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt