From: Steffen Klassert <steffen.klassert@secunet.com>
To: "Cen Zhang (Microsoft)" <blbllhy@gmail.com>
Cc: <herbert@gondor.apana.org.au>, <davem@davemloft.net>,
<edumazet@google.com>, <kuba@kernel.org>, <pabeni@redhat.com>,
<horms@kernel.org>, <netdev@vger.kernel.org>,
<linux-kernel@vger.kernel.org>,
<AutonomousCodeSecurity@microsoft.com>, <xmei5@asu.edu>,
<tgopinath@linux.microsoft.com>, <kys@microsoft.com>
Subject: Re: [PATCH net v2] xfrm: hold net_device reference under RCU in bundle creation
Date: Thu, 3 Sep 2026 09:35:04 +0200 [thread overview]
Message-ID: <apkjKMgkC35QKnHq@secunet.com> (raw)
In-Reply-To: <20260826201745.43267-1-blbllhy@gmail.com>
On Wed, Aug 26, 2026 at 04:17:45PM -0400, Cen Zhang (Microsoft) wrote:
> From: "Cen Zhang (Microsoft Security FORGE Labs)" <blbllhy@gmail.com>
>
> xfrm_bundle_create() and xfrm_create_dummy_bundle() read dst->dev into
> a local pointer without taking a device reference, then pass it to
> xfrm_fill_dst(). A concurrent RTM_DELLINK replaces dst->dev via
> dst_dev_put() and frees the old net_device, causing a use-after-free
> when xfrm6_fill_dst() later dereferences the stale dev pointer.
>
> BUG: KASAN: slab-use-after-free in xfrm6_fill_dst+0x82c/0x860
> (net/ipv6/xfrm6_policy.c:86 netdev_hold())
> Read of size 8 at addr ffff8880142fe588 by task exploit/153
> Call Trace:
> xfrm6_fill_dst+0x82c/0x860
> xfrm_resolve_and_create_bundle+0x21d4/0x2bd0
> xfrm_lookup_with_ifid+0x485/0x1640
> ip6_dst_lookup_flow+0x19b/0x1e0
> udpv6_sendmsg+0x1443/0x2dd0
>
> Fix this by reading dst->dev via dst_dev_rcu() and keeping the RCU
> read-side critical section active until xfrm_fill_dst() has taken the
> required device references.
>
> Fixes: 25ee3286dcbc ("[IPSEC]: Merge common code into xfrm_bundle_create")
> Fixes: a0073fe18e71 ("xfrm: Add a state resolution packet queue")
> Suggested-by: Steffen Klassert <steffen.klassert@secunet.com>
> Reported-by: Xiang Mei (Microsoft) <xmei5@asu.edu>
> Link: https://lore.kernel.org/all/20260820200245.44312-1-blbllhy@gmail.com/
> Cc: AutonomousCodeSecurity@microsoft.com
> Assisted-by: GitHub-Copilot:claude-opus-4.6
> Signed-off-by: Cen Zhang (Microsoft Security FORGE Labs) <blbllhy@gmail.com>
Applied, thanks a lot!
prev parent reply other threads:[~2026-09-03 7:35 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-26 20:17 [PATCH net v2] xfrm: hold net_device reference under RCU in bundle creation Cen Zhang (Microsoft)
2026-09-03 7:35 ` Steffen Klassert [this message]
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