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 DC9662F3C18; Tue, 1 Sep 2026 13:40:06 +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=1788270008; cv=none; b=g2B89950Pp/uGE7V+37C4m9bjoD6RAr6YESHG203VjnChZXcqKRZTdBI5dSEWTfMJ/D922KwlOUVRicNZZrT70y0SYHPwAvYYIyOAcKQFHcnHfFXyyoOgfpraNkSkA6a3GmkT54evth26FLdRPrOpV60yU+QUvAS2RXjeZP1pu8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788270008; c=relaxed/simple; bh=aJetiop332TzGMjtNxCwp2osCzOlN1SMdSvmKASa+aI=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=NXOC8IiC6+cbiIoxRgrYIQoxPaxBhHRex0tdNgNAiHQRtfb69ArL4NSaUeatOZ+zFs0XlGz+JFe2zs7mno7BnHPqV+ltf3ZKZ1Pa4R2DkaVgVt4wIYlW3yIVyPRT70hphg5dsa+HF9k4nmNouSr1JslI0QlkqDSJ6DfaG4IOLsQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BnKW3vZx; 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="BnKW3vZx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 33E451F00A3D; Tue, 1 Sep 2026 13:40:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788270006; bh=f7DIO5UFdyzmop+0FickQyJR+upbMPxvd7WYzoH5UvM=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=BnKW3vZxrxuHwWNycigqeLIWzN/bOxUePAv20ekKVg76KgBoSO/CBbZap98SVdTAP TOOT3FJ4yUOpqU+VHTt4a0apDE7wd3cOt8Cx2Pmb0eNUPhhkpuLNv2aSFrZnLMYrs3 5ViPncRorCJG8+qMrpSfEMLz8JhPWjXe6pDVtxG1/IEhTrxKJkY9FuHxksW0phQH5w nfaDoiyG+80XdfrK8KawpejLGFFYfc1j6a9SKI1M9pZKlKKwqxwR6dZVT8t05hncEa zYHrIukzZNdvDVF07inmaZhEXuZM/BN+JQ+a451444JdPFrbWHeNO9wjVC/Y5xNs+4 nenTP95lMWdDg== From: Jeff Layton Date: Tue, 01 Sep 2026 09:39:40 -0400 Subject: [PATCH v5 02/15] NFSD: validate transport name in listener_set before serv creation Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260901-nfsd-nl-hang-v5-2-a540d86668b0@kernel.org> References: <20260901-nfsd-nl-hang-v5-0-a540d86668b0@kernel.org> In-Reply-To: <20260901-nfsd-nl-hang-v5-0-a540d86668b0@kernel.org> To: Chuck Lever , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey , Trond Myklebust , Anna Schumaker , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Shuah Khan Cc: Slawomir Stepien , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Trond Myklebust , linux-kselftest@vger.kernel.org, Jeff Layton X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=2761; i=jlayton@kernel.org; h=from:subject:message-id; bh=aJetiop332TzGMjtNxCwp2osCzOlN1SMdSvmKASa+aI=; b=owEBbQKS/ZANAwAKAQAOaEEZVoIVAcsmYgBqltWuaHsNrR6zYYfSMArd5NsyaG532BAv1IbcP lDaHurfePSJAjMEAAEKAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCapbVrgAKCRAADmhBGVaC FSz3D/9mEWvGywz0hP/R1Ypu96onbBI6AKRDb48NcEZ6LdvoAVUbRrNw3GEr3fydzFtiQF50XLu zJBrs1AxMLlUvQYklx0Ihe3Zr0xFuYWdU0YKefxx6fkyClVTkDuh+E7MEm3/7FtPYiT9KWK5N5L 7iPFYSH8ax0v880YAmEWSew/+VqIJZRlF7PbxTwq4VsqevLPl8bcXRf67A5k/4s6MvNmEXraweG s7Hojn1Q3j8+bAzRKH3qcKVbHFRI1h8ocdCCZq3e3XMqy5oUyd1ONJRpYPE50nDcTSgpn4g9ips HsDWHCqLPOP1O5HtUqNK4bvlu0vJo1W+Etv5vewWHzJhIXkIc8RrcyUJClZtEgi02zaAfBTYrS4 7ttN9eQdQsClk8bKcKPU3ToKh04KtXJFBkTal6W2NKKOOe8odfoSIXU4s+BoHIIG9b37HczowCE bmVJz+yqB3K/DKIvap/CJOM0c1aCXDsV3da15QJ3+xto8Ray+vQLsmWx5yUhasIIwQ5jdmgUJLk mtibP9A1SRG1Ch1rxxhkZDXdcYVOIUILyTpzHt0VG8QVnfrtyaUHKyWpfRUpW5D1FxMhqRzYFJ2 uGEy2mauYPQrFOtZV/3xmVu1LPG3T2mNAcgl1mPfvd9ahRHVylf4jYCV89wmu6vJigAJQXi/s+G JOibkyb9UzgQIUQ== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 nfsd_nl_listener_set_doit() holds nfsd_mutex for the whole listener teardown and rebuild. The code checks NFSD_A_SOCK_TRANSPORT_NAME for presence only, and not for content. An arbitrary name therefore reaches svc_xprt_create_from_sa(). There, a name that matches no registered class calls request_module("svc%s", name). That call is a TASK_KILLABLE usermode helper upcall, and it runs under nfsd_mutex. Check the name against the classes that NFSD can create: tcp, udp and rdma. The check goes in nfsd_nl_validate_listeners(), which runs before the code takes nfsd_mutex. The rejection names the offending attribute through extack, since -EPROTONOSUPPORT on its own does not say which entry carried the bad name. This narrows the upcall. It does not remove it. NFSD accepts "rdma" without a condition, so on a kernel that does not build svcrdma the name still reaches request_module("svcrdma") under nfsd_mutex. That is necessary for the modular case, where the autoload is legitimate. Fixes: 16a471177496 ("NFSD: add listener-{set,get} netlink command") Assisted-by: LLM Link: https://syzkaller.appspot.com/bug?extid=c7eae0eb80858a2dba0f Signed-off-by: Jeff Layton --- fs/nfsd/nfsctl.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index b6f4d66f612a..d8135f38e69f 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1995,6 +1995,23 @@ int nfsd_nl_version_get_doit(struct sk_buff *skb, struct genl_info *info) return err; } +/* + * Transport classes NFSD knows how to instantiate. Vetting the name here + * keeps a bogus string from reaching svc_xprt_create_from_sa(), where an + * unknown name triggers a request_module("svc%s", name) upcall under + * nfsd_mutex. + */ +static bool nfsd_nl_transport_supported(const char *name) +{ + static const char * const supported[] = { "tcp", "udp", "rdma" }; + int i; + + for (i = 0; i < ARRAY_SIZE(supported); i++) + if (!strcmp(name, supported[i])) + return true; + return false; +} + /* Upper bound on the number of listeners a single request may carry. */ #define NFSD_NL_LISTENER_MAX 1024 @@ -2032,6 +2049,13 @@ static int nfsd_nl_validate_listeners(struct genl_info *info) if (!tb[NFSD_A_SOCK_ADDR] || !tb[NFSD_A_SOCK_TRANSPORT_NAME]) return -EINVAL; + if (!nfsd_nl_transport_supported(nla_data(tb[NFSD_A_SOCK_TRANSPORT_NAME]))) { + NL_SET_ERR_MSG_ATTR(info->extack, + tb[NFSD_A_SOCK_TRANSPORT_NAME], + "unsupported transport name"); + return -EPROTONOSUPPORT; + } + sa = nla_data(tb[NFSD_A_SOCK_ADDR]); if (nla_len(tb[NFSD_A_SOCK_ADDR]) < sizeof(sa->sa_family)) return -EINVAL; -- 2.55.0