From: Jakub Kicinski <kuba@kernel.org>
To: Jeongjun Park <aha310510@gmail.com>
Cc: Paolo Abeni <pabeni@redhat.com>,
wei.liu@kernel.org, paul@xen.org, davem@davemloft.net,
edumazet@google.com, madhuparnabhowmik04@gmail.com,
xen-devel@lists.xenproject.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net] net/xen-netback: prevent UAF in xenvif_flush_hash()
Date: Wed, 28 Aug 2024 17:06:57 -0700 [thread overview]
Message-ID: <20240828170657.5f493cc6@kernel.org> (raw)
In-Reply-To: <CAO9qdTGHJw-SUFH9D16N5wSn4KmaMUcX+GVFuEFu+jqMb3HU1g@mail.gmail.com>
On Wed, 28 Aug 2024 21:52:12 +0900 Jeongjun Park wrote:
> > The loop runs with irq disabled, the RCU critical section extends over
> > it, uninterrupted.
>
> Basically, list_for_each_entry_rcu is specified to be used under the protection
> of rcu_read_lock(), but this is not the case with xenvif_new_hash(). If it is
> used without the protection of rcu_read_lock(), kfree is called immediately
> after the grace period ends after the call to kfree_rcu() inside
> list_for_each_entry_rcu, so the entry is released, and a UAF occurs when
> fetching with ->next thereafter.
You cut off and didn't answer Paolo's question whether you have a splat
/ saw this actually cause a crash or a KASAN warning.
next prev parent reply other threads:[~2024-08-29 0:07 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-22 18:11 [PATCH net] net/xen-netback: prevent UAF in xenvif_flush_hash() Jeongjun Park
2024-08-27 11:19 ` Paolo Abeni
2024-08-27 14:14 ` Jakub Kicinski
2024-08-28 12:52 ` Jeongjun Park
2024-08-29 0:06 ` Jakub Kicinski [this message]
2024-08-29 0:20 ` patchwork-bot+netdevbpf
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