From: Chuck Lever <cel@kernel.org>
To: Trond Myklebust <trondmy@kernel.org>,
Anna Schumaker <anna@kernel.org>,
Jeff Layton <jlayton@kernel.org>,
"Cen Zhang (Microsoft)" <cenzhang@linux.microsoft.com>
Cc: NeilBrown <neil@brown.name>,
Olga Kornievskaia <okorniev@redhat.com>,
Dai Ngo <Dai.Ngo@oracle.com>, Tom Talpey <tom@talpey.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Simon Horman <horms@kernel.org>,
linux-nfs@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org,
AutonomousCodeSecurity@microsoft.com,
Francis Perron <francis@akrites.dev>,
tgopinath@linux.microsoft.com, kys@microsoft.com
Subject: Re: [PATCH] sunrpc: reject AUTH_TLS on backchannel to prevent NULL-deref in svcauth_tls_accept
Date: Fri, 25 Sep 2026 11:08:26 -0400 [thread overview]
Message-ID: <179034889150.511047.410064411360925786.b4-ty@b4> (raw)
In-Reply-To: <20260925015251.21168-1-cenzhang@linux.microsoft.com>
On Thu, 24 Sep 2026 21:52:51 -0400, Cen Zhang (Microsoft) wrote:
> svcauth_tls_accept() dereferences rqstp->rq_xprt unconditionally when
> it tests xprt->xpt_ops->xpo_handshake, but on the NFSv4.1 backchannel
> path (svc_process_bc), rq_xprt is NULL because no server-side transport
> exists. A malicious NFS server can send AUTH_TLS (flavor 7) on the
> backchannel to trigger a NULL pointer dereference in the client kernel.
>
> general protection fault, probably for non-canonical address
> 0xdffffc0000000001
> KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
> RIP: 0010:svcauth_tls_accept+0x258/0x820
> svc_authenticate+0x2ab/0x3e0
> svc_process_common+0x8ff/0x1cf0
> svc_process_bc+0x5a8/0xbb0
> nfs4_callback_svc+0xcf/0x170
>
> [...]
Applied to nfsd-testing, thanks!
[1/1] sunrpc: reject AUTH_TLS on backchannel to prevent NULL-deref in svcauth_tls_accept
commit: 32eb1a60b456980761cf7a9cee8f907fdc08afb8
--
Chuck Lever
prev parent reply other threads:[~2026-09-25 15:08 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-25 1:52 [PATCH] sunrpc: reject AUTH_TLS on backchannel to prevent NULL-deref in svcauth_tls_accept Cen Zhang (Microsoft)
2026-09-25 15:08 ` Chuck Lever [this message]
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