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 AB459442B1B; Tue, 11 Aug 2026 12:03:13 +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=1786449794; cv=none; b=NoMtoE+sw13FCNFcKRp0o9dV8W8UH3BBgqz9+yF7kWHfk0TRpB+RwhkfMl1KmsaHTJ8+nEh5rqv3+bhy5rMjP9Avt48lk/364lVBX3tH4eicBBVJI6Q2EejaKK4OPNK+GNzsXcFFYYMTt6du6CXCGe3YOlf+LrJOhB+hCVEiZCc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786449794; c=relaxed/simple; bh=5rSg4dAcvVQv/gwh6ajdjqTKnjmHWmRK73iIdvgeZj0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=nfVp7XmIrQzNwJsmKz4mH1QRJ0eFhW4QkhTfpJ1FX8BS5xrkP9T3wEPknaGBL7RI597merr4HGtQovXQ4pVqKbjJcUlj1hP94cXcLqhRFIAsCZt1NdmFhsmHlhLf5Ji9GJkVbyGoLQ9w4UcJm0kH2YsNkEfZxKAdrqfHFq8gZOE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=a3FtI9uS; 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="a3FtI9uS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E2CE11F00A3A; Tue, 11 Aug 2026 12:03:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786449793; bh=q9kotpnhc3C3OSb7dmtZK9XgIYyfRPrPIg0cQGtxKB0=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=a3FtI9uSq4+QlpfOi/sG8KFmljaR7k5HyLNSe1hBtUZfqKKr5+Wcg0/dZ3u7+Gdh+ My3I8vxK9pQuhONkAJBG8t0O8w5kQYiaAmFr15bOb03KF6yVioYDqZNPYgfb1tDj4Y RUzZCkhFGtjd2cvaAb91t+uWGL5LLsUQ2ii7jhkLUvp1IFSMPM67CzbaX+sh+j/yij +FtES12gwc1+tpSP2K/yF30l28YVH5b3UhMWsP+mV3OSidInZhsLfT30HN4p9gRP/T vWkWjmwNyAo0Cf2PwQMfledQORqLcdJ0GG7Ln9pPJf/dL+GDvtni7GSfhthZYJg3Fw qTEnmdm63K37g== From: Jeff Layton Date: Tue, 11 Aug 2026 08:03:00 -0400 Subject: [PATCH v2 1/8] 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: <20260811-nfsd-nl-hang-v2-1-c0c92b3953c3@kernel.org> References: <20260811-nfsd-nl-hang-v2-0-c0c92b3953c3@kernel.org> In-Reply-To: <20260811-nfsd-nl-hang-v2-0-c0c92b3953c3@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 , "J. Bruce Fields" , Shuah Khan Cc: 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=2981; i=jlayton@kernel.org; h=from:subject:message-id; bh=5rSg4dAcvVQv/gwh6ajdjqTKnjmHWmRK73iIdvgeZj0=; b=owEBbQKS/ZANAwAKAQAOaEEZVoIVAcsmYgBqew98cqbUEml+nrQcyt4CLQwFwc/dSd408L7xi hsc1X+aIcCJAjMEAAEKAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCansPfAAKCRAADmhBGVaC FQHgEACEMbOWPsNYfHKRaxjwnybKG3uRSazAlvcOsRI05qbUxbhvcV5uSLxKNyzHEwP1dSho3ld r5aOJkjj+J0er3z6SqIkA5/jDKvUVmFeqqvUlXA1dNHD5HrsHK8BoDFbaHg5N839JHgxd36xH4K 4ZmQWvrBbJPAVKztEZxx5MShzbQmmP/snuQWrlouyqsw6IL3J6YWTsMwegU1lZEhAx90CVLtgAc MFJxfs9kO5C6aiB/vuFMTWU6b+tsqFX3+ym/kvnsJTarFJm4XWfZNaPIMDrcJILoYjgrpqMdy3g INvKeGoTjeklp5lfkqnvDLPDlIGAREzH2IseaNxr3TTemqWUfq8pgPkbaTlGttCicYJMOBr+vPg 5ZLutSlw0gJHFk082YURk7Gq+9MTOU5dEl9oM0hbjmkU5knjTn9DHGbGy+xsE7wenQiLy7/U3G7 FgBqukeadKf8/dLf4R9zkpyF4vHEC1F6hN4R3T2f130qisM+nBX31ogGrYK2xLb0mTBo+/qAiIu Dl6RcPp+c6M24yK+/MkMlBGhtxP0nrr5vC6J+vB/m+YWFCs1erzt2Pv9bMt5XwGpETRTlD85PuE QHL6HFWW+LDJIGJInN9jguCqXCXEGKEuw5dqeFjjbGPkq+mCJwqaSNV6Paso/TTnBvmKHDfhp1q mA93ipKDIim3+1A== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 nfsd_nl_listener_set_doit() holds nfsd_mutex across the whole listener teardown/rebuild. NFSD_A_SOCK_TRANSPORT_NAME is only checked for presence, not content, so an arbitrary name reaches svc_xprt_create_from_sa(), where a name matching no registered class triggers request_module("svc%s", name) -- a TASK_KILLABLE usermode-helper upcall run under nfsd_mutex. Vet the name against the classes NFSD can instantiate (tcp, udp, rdma) in nfsd_nl_validate_listeners(), which runs before nfsd_mutex is taken. This narrows the upcall rather than removing it. "rdma" is accepted unconditionally, so on a kernel where svcrdma is not built it still reaches request_module("svcrdma") under nfsd_mutex -- as it must for the modular case, where autoloading is legitimate. Assisted-by: LLM Link: https://syzkaller.appspot.com/bug?extid=c7eae0eb80858a2dba0f Signed-off-by: Jeff Layton --- fs/nfsd/nfsctl.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 4e5e083d8477..e5844d8454b8 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1975,14 +1975,31 @@ 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; +} + /** * nfsd_nl_validate_listeners - sanity-check the listener list from userland * @info: netlink metadata and command arguments * * Walk every NFSD_A_SERVER_SOCK_ADDR attribute and confirm that each entry * is well-formed: it parses against the policy, carries both an address and - * a transport name, and the address is long enough for its family. Doing - * this up front lets the callers below assume every entry is valid and + * a supported transport name, and the address is long enough for its family. + * Doing this up front lets the callers below assume every entry is valid and * guarantees we make no changes when the request is malformed. * * Return: 0 if every entry is valid, or a negative errno otherwise. @@ -2006,6 +2023,9 @@ 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]))) + 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