From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BDA7E4C041E; Mon, 8 Jun 2026 14:58:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780930692; cv=none; b=gu25gUv0x8wdUxcQsvnXhPGPR9Qxo1mo+sbdQO5n7ouWUN1IhxdR1FUj/e9tbnnVC7liBpTGDFVhk0uSzN+IhmgwlcPhayw2UqZWP97ximHdhf2nhR6TVpJHLaxYoCxYB78KZ6tJ35yrmbHFz2uITQa1XIZzNUBunrvGYeiN8iE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780930692; c=relaxed/simple; bh=NmTODon786G03AyBnlavBd/xXPk6GHimwEnA6y6eNwM=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=OFUHuvSSuKAYAR3aeqScK5yRdSpAwQ4tkUlGX8VM6QfCXiD1MD+dVZm1xZsy+EDdQaXyDcffBiMnRIFQMr6n/F+OPSdGySJi1VdWxcOgJ4pri8SnJ6BbDlzRlBlTbLb6h4lEo+dLgznrRx5T4VfM8UaDcmcEO62ZHZEBA/Pq48c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ez6UEnwA; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Ez6UEnwA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2584A1F00893; Mon, 8 Jun 2026 14:58:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780930682; bh=bgghpU4brkUy2PyZnD2Jwp6r5i79xsjJS0yYeBaj9CA=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=Ez6UEnwA9OURmSMJHZNSkNgO9ce/XVCX56uaiUk4NqfKABLUwPMHpjopJXl+8JdRT Ct7o73OHv6TRAodMqSarLo2U2KVxxMDGUts+fbzNZKCOuTFEha9UPdiie2E71H3ogp QaCW/i6MvSU0HpAdrPFlVElbTaSJ9eZAo4iwpqcRw5YUlqPlLuhIjWLsaWPctQlASI HyTyeNFmX6HidziW0vx3zVGaJ4E8cOVqyP2lqwlYdk9EMfTFs0HLoKJyMyPdVlu4jx AJoyHCIf+cfz6hPO5GW+377hJ4qf8CBA097wlKOf2iCD2ovueyMDH35Z7d3/ntbDXe PQpCzi6QcLKGg== Message-ID: <417778feec71dd4a2db03bfca4b74cf0ee41dedd.camel@kernel.org> Subject: Re: [PATCH] SUNRPC: check rpc_sockaddr2uaddr() return value in rpcb_register_inet4/6 From: Jeff Layton To: Weiming Shi , linux-nfs@vger.kernel.org, Trond Myklebust , Anna Schumaker Cc: Chuck Lever , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Xiang Mei Date: Mon, 08 Jun 2026 10:57:59 -0400 In-Reply-To: <20260607140645.2198574-2-bestswngs@gmail.com> References: <20260607140645.2198574-2-bestswngs@gmail.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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2026-06-07 at 07:06 -0700, Weiming Shi wrote: > 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. >=20 > The crash reproduces under failslab on v6.12; with KASAN the NULL > dereference surfaces as a fault on the shadow of address zero: >=20 > 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 >=20 > 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. >=20 > Mirror that handling: bail out with -ENOMEM when rpc_sockaddr2uaddr() > returns NULL, before the address is fed into the encoder. >=20 > 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(+) >=20 > 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) { Reviewed-by: Jeff Layton