From: Steffen Klassert <steffen.klassert@secunet.com>
To: "Xiang Mei (Microsoft)" <xmei5@asu.edu>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
"David S . Miller" <davem@davemloft.net>,
<netdev@vger.kernel.org>, Simon Horman <horms@kernel.org>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
<AutonomousCodeSecurity@microsoft.com>,
<tgopinath@linux.microsoft.com>, <kys@microsoft.com>
Subject: Re: [PATCH ipsec] xfrm6: clear dst.dev on error to avoid double netdev_put in xfrm6_fill_dst()
Date: Tue, 7 Jul 2026 08:34:21 +0200 [thread overview]
Message-ID: <akyd7YVSczkMzK-h@secunet.com> (raw)
In-Reply-To: <20260702010516.221830-1-xmei5@asu.edu>
On Thu, Jul 02, 2026 at 01:05:16AM +0000, Xiang Mei (Microsoft) wrote:
> On the error path where in6_dev_get(dev) returns NULL, xfrm6_fill_dst()
> releases the device reference with netdev_put() but leaves
> xdst->u.dst.dev set. dst_destroy() later calls netdev_put(dst->dev)
> again, so the same net_device reference is released twice, underflowing
> its refcount (ref_tracker WARNING + "unregister_netdevice: waiting for
> <dev> to become free").
>
> Clear xdst->u.dst.dev after the netdev_put(), the same way the XFRM
> device-offload paths xfrm_dev_state_add() and xfrm_dev_policy_add() in
> net/xfrm/xfrm_device.c NULL ->dev when releasing the reference on error.
>
> ref_tracker: reference already released.
> ref_tracker: allocated in:
> xfrm6_fill_dst (net/ipv6/xfrm6_policy.c:86)
> ...
> udpv6_sendmsg (net/ipv6/udp.c:1696)
> ...
> ref_tracker: freed in:
> xfrm6_fill_dst (net/ipv6/xfrm6_policy.c:90)
> ...
> WARNING: lib/ref_tracker.c:322 at ref_tracker_free+0x58b/0x780
> dst_destroy (net/core/dst.c:115)
> rcu_core
> handle_softirqs
> ...
>
> Fixes: 84c4a9dfbf43 ("xfrm6: release dev before returning error")
> Reported-by: AutonomousCodeSecurity@microsoft.com
> Signed-off-by: Xiang Mei (Microsoft) <xmei5@asu.edu>
Applied, thanks a lot!
next prev parent reply other threads:[~2026-07-07 6:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-02 1:05 [PATCH ipsec] xfrm6: clear dst.dev on error to avoid double netdev_put in xfrm6_fill_dst() Xiang Mei (Microsoft)
2026-07-07 6:34 ` Steffen Klassert [this message]
2026-07-07 18:18 ` Xiang Mei
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