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Sun, 07 Jun 2026 07:30:31 -0700 (PDT) Received: from fx.tailc0aff1.ts.net ([206.206.192.132]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3074db5610esm13877187eec.4.2026.06.07.07.30.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 07 Jun 2026 07:30:30 -0700 (PDT) From: Weiming Shi To: linux-nfs@vger.kernel.org, Trond Myklebust , Anna Schumaker Cc: Chuck Lever , Jeff Layton , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Weiming Shi , Xiang Mei Subject: [PATCH] SUNRPC: check rpc_sockaddr2uaddr() return value in rpcb_register_inet4/6 Date: Sun, 7 Jun 2026 07:06:46 -0700 Message-ID: <20260607140645.2198574-2-bestswngs@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" rpcb_register_inet4() and rpcb_register_inet6() store the result of rpc_sockaddr2uaddr() into map->r_addr without checking it for NULL. rpc_sockaddr2uaddr() returns NULL when its final kstrdup() fails, and the unchecked NULL is then carried into the synchronous RPCBPROC_SET encode path: rpcb_register_call() -> rpc_call_sync() -> rpcb_enc_getaddr() -> encode_rpcb_string(), whose first statement is strlen(string), dereferencing NULL and oopsing the kernel. The crash reproduces under failslab on v6.12; with KASAN the NULL dereference surfaces as a fault on the shadow of address zero: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000 [#1] PREEMPT SMP KASAN RIP: 0010:strlen (lib/string.c:409) Call Trace: encode_rpcb_string (net/sunrpc/rpcb_clnt.c:890) rpcb_enc_getaddr (net/sunrpc/rpcb_clnt.c:910) rpcauth_wrap_req_encode (net/sunrpc/auth.c:745) call_encode (net/sunrpc/clnt.c:1966) __rpc_execute (net/sunrpc/sched.c:952) rpc_run_task (net/sunrpc/clnt.c:1243) rpc_call_sync (net/sunrpc/clnt.c:1272) rpcb_v4_register (net/sunrpc/rpcb_clnt.c:500) svc_generic_rpcbind_set nfsd_rpcbind_set svc_register svc_setup_socket svc_addsock write_ports nfsctl_transaction_write vfs_write The crash is reachable when an in-kernel RPC service (nfsd, lockd, nfs-callback) registers with the local rpcbind under enough memory pressure for the small GFP_KERNEL kstrdup() in rpc_sockaddr2uaddr() to fail. The asynchronous getport path already handles this exact failure mode by returning -ENOMEM; only the two register helpers omit the check. Mirror that handling: bail out with -ENOMEM when rpc_sockaddr2uaddr() returns NULL, before the address is fed into the encoder. Fixes: d77385f23830 ("SUNRPC: Fix rpc_sockaddr2uaddr") Reported-by: Xiang Mei Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Weiming Shi --- net/sunrpc/rpcb_clnt.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/sunrpc/rpcb_clnt.c b/net/sunrpc/rpcb_clnt.c index 6aa372188c86..4c0b7fefee4e 100644 --- a/net/sunrpc/rpcb_clnt.c +++ b/net/sunrpc/rpcb_clnt.c @@ -490,6 +490,8 @@ static int rpcb_register_inet4(struct sunrpc_net *sn, int result; =20 map->r_addr =3D rpc_sockaddr2uaddr(sap, GFP_KERNEL); + if (!map->r_addr) + return -ENOMEM; =20 msg->rpc_proc =3D &rpcb_procedures4[RPCBPROC_UNSET]; if (port !=3D 0) { @@ -516,6 +518,8 @@ static int rpcb_register_inet6(struct sunrpc_net *sn, int result; =20 map->r_addr =3D rpc_sockaddr2uaddr(sap, GFP_KERNEL); + if (!map->r_addr) + return -ENOMEM; =20 msg->rpc_proc =3D &rpcb_procedures4[RPCBPROC_UNSET]; if (port !=3D 0) { --=20 2.43.0