From fd22370226a0d8109045d0831fd5aaadee921693 Mon Sep 17 00:00:00 2001 From: Weiming Shi Date: Sun, 7 Jun 2026 07:06:46 -0700 Subject: [PATCH] SUNRPC: check rpc_sockaddr2uaddr() return value in rpcb_register_inet4/6 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 Reviewed-by: Jeff Layton Signed-off-by: Trond Myklebust --- 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) {