From: David Howells <dhowells@redhat.com>
To: Simon Horman <horms@kernel.org>
Cc: dhowells@redhat.com, netdev@vger.kernel.org,
Marc Dionne <marc.dionne@auristor.com>,
Jakub Kicinski <kuba@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>,
linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org,
Jeffrey Altman <jaltman@auristor.com>,
Jarkko Sakkinen <jarkko@kernel.org>,
keyrings@vger.kernel.org, stable@kernel.org
Subject: Re: [PATCH net v5 07/10] afs: Create a server appdata key
Date: Tue, 04 Aug 2026 16:46:08 +0100 [thread overview]
Message-ID: <2804996.1785858368@warthog.procyon.org.uk> (raw)
In-Reply-To: <20260803160627.GL51943@horms.kernel.org>
Simon Horman <horms@kernel.org> wrote:
> [Severity: Critical]
> This is a pre-existing issue, but is it safe to cast and dereference peer_data
> here?
>
> When a network CHALLENGE packet arrives and is processed in the OOB queue in
> afs_respond_to_challenge(), it reads peer_data and casts it to an afs_server
> pointer.
>
> Since the code dereferences this pointer without holding rcu_read_lock() or
> taking a reference on the server object, what happens if the server is
> concurrently destroyed or updated?
>
> If peer_data is set to 0, this causes a direct NULL dereference. If the
> server memory is freed, could this result in a use-after-free triggered by a
> remote attacker?
Note that the OOB code is removed by these patches.
The other two issues here need addressing, though for one of them, the fix
will need to go via the vfs tree.
David
next prev parent reply other threads:[~2026-08-04 15:46 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-29 16:00 [PATCH net v5 00/10] rxrpc: Fix CHALLENGE packet handling David Howells
2026-07-29 16:00 ` [PATCH net v5 01/10] rxrpc: Fix sendmsg to not return an error if last packet queued David Howells
2026-07-29 16:00 ` [PATCH net v5 02/10] rxrpc: Fix packet encryption error handling David Howells
2026-08-03 16:02 ` Simon Horman
2026-07-29 16:01 ` [PATCH net v5 03/10] rxrpc: Fix update of call->tx_pending without holding lock David Howells
2026-07-29 16:01 ` [PATCH net v5 04/10] rxrpc: Fix generation of notifications after call completion David Howells
2026-07-29 16:01 ` [PATCH net v5 05/10] rxrpc: Expand abort trace enum David Howells
2026-07-29 16:01 ` [PATCH net v5 06/10] keys: Add refcounting to user-defined key type payload David Howells
2026-07-29 16:01 ` [PATCH net v5 07/10] afs: Create a server appdata key David Howells
2026-08-03 16:06 ` Simon Horman
2026-08-04 15:46 ` David Howells [this message]
2026-07-29 16:01 ` [PATCH net v5 08/10] rxrpc: Pass appdata key to rxrpc_call and thence to rxrpc_bundle David Howells
2026-07-29 16:01 ` [PATCH net v5 09/10] rxrpc: Fix CHALLENGE packet overqueuing and simplify RESPONSE generation David Howells
2026-07-29 16:01 ` [PATCH net v5 10/10] rxrpc: Remove OOB challenge/response code David Howells
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