From: Weiming Shi <bestswngs@gmail•com>
To: linux-nfs@vger•kernel.org, Trond Myklebust <trondmy@kernel•org>,
Anna Schumaker <anna@kernel•org>
Cc: Chuck Lever <chuck.lever@oracle•com>,
Jeff Layton <jlayton@kernel•org>, NeilBrown <neil@brown•name>,
Olga Kornievskaia <okorniev@redhat•com>,
Dai Ngo <Dai.Ngo@oracle•com>, Tom Talpey <tom@talpey•com>,
netdev@vger•kernel.org, linux-kernel@vger•kernel.org,
Weiming Shi <bestswngs@gmail•com>, Xiang Mei <xmei5@asu•edu>
Subject: [PATCH] SUNRPC: check rpc_sockaddr2uaddr() return value in rpcb_register_inet4/6
Date: Sun, 7 Jun 2026 07:06:46 -0700 [thread overview]
Message-ID: <20260607140645.2198574-2-bestswngs@gmail.com> (raw)
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 <xmei5@asu•edu>
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Weiming Shi <bestswngs@gmail•com>
---
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;
map->r_addr = rpc_sockaddr2uaddr(sap, GFP_KERNEL);
+ if (!map->r_addr)
+ return -ENOMEM;
msg->rpc_proc = &rpcb_procedures4[RPCBPROC_UNSET];
if (port != 0) {
@@ -516,6 +518,8 @@ static int rpcb_register_inet6(struct sunrpc_net *sn,
int result;
map->r_addr = rpc_sockaddr2uaddr(sap, GFP_KERNEL);
+ if (!map->r_addr)
+ return -ENOMEM;
msg->rpc_proc = &rpcb_procedures4[RPCBPROC_UNSET];
if (port != 0) {
--
2.43.0
next reply other threads:[~2026-06-07 14:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-07 14:06 Weiming Shi [this message]
2026-06-08 14:57 ` [PATCH] SUNRPC: check rpc_sockaddr2uaddr() return value in rpcb_register_inet4/6 Jeff Layton
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