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 218903932FA; Fri, 28 Aug 2026 16:37:48 +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=1787935070; cv=none; b=o2H5sxyeucw6ywcffOLB0lWZTimB3Dh6RT/A8fNdkH3i92JNTtzSlpcjD+m7ZestVNxH5YELSI8ll9nJYBHkjbv1btWIk+QyZgYNgYKPjHQJ0thYtpwxRZxBdC/JHov7zZAthQOvVXLhxNeiFEvcxYFAxdc7IdLXmY4QAfmDJhk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787935070; c=relaxed/simple; bh=aJetiop332TzGMjtNxCwp2osCzOlN1SMdSvmKASa+aI=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Uy4GjlaN2WUHJoSRbhhOuHX2cp43Zvv3BYU735LgTkWvnjEyJ/A8XhcnFJRPti6bsz+jOLrWj0VfV1SND1bE11C+PgMkVUq+TTTH91yPTGYTg/niUw1rZB+CTJ6sMJnLf9hk5lHZMvNEeN+wq0QBx29r5D3FXm8bt6WGKqBigAA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ljUOfsfA; 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="ljUOfsfA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F25581F000E9; Fri, 28 Aug 2026 16:37:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787935068; bh=f7DIO5UFdyzmop+0FickQyJR+upbMPxvd7WYzoH5UvM=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=ljUOfsfAfBRR6ZCVhGU5c88WgatmyOwaDNfeGJh3Rkn8RjINg51BC001MuqwgrmEe qW9sEjUi72nO4ilolSkXv2LF/SNnkxuq1iWfPrX43HYLZHtquPXrYR/4nry1glZAw/ 426BdCqnLpk25gISMdfQYgSftqIm3R6CJagLe9Rn5QSmKxMCxrRtLcRwzIetBSui70 +jlLTADB7YJmSRLxeBowyPgTBrxFkFXEwDqbX2Pvq7fjtlMO1UKQ760STEcFtIrOco 1ki5XjiI/6JHUU7X0pog/p5XayzhPqY1yjEjypAsQxGIXyrAh+lK9dEY/cwopvlWm4 2lswT4lknaFwg== From: Jeff Layton Date: Fri, 28 Aug 2026 12:37:32 -0400 Subject: [PATCH v3 02/14] 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: <20260828-nfsd-nl-hang-v3-2-55026685c75d@kernel.org> References: <20260828-nfsd-nl-hang-v3-0-55026685c75d@kernel.org> In-Reply-To: <20260828-nfsd-nl-hang-v3-0-55026685c75d@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/ZANAwAKAQAOaEEZVoIVAcsmYgBqkblU7ipDBR9hOHCBw4J3hHZKeSediS87zPMNB ECizBuP8r6JAjMEAAEKAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCapG5VAAKCRAADmhBGVaC FfUYEADUjJjbSWHOdtHJlppRBlsFrh+hg7vLLU5wqjzVhOgWcKenRqsfmwHGoiOEcPNMN+socBH AGqy5C5eWvwBeqNUZyMLkJTvxGSavUR8O1eEtj/NA5ybsOGCHebwhW2aRAw2QxzXJcHU2lq9ikr 6GasDNLUQ9zV6RpsnEGM8K72NCopXM6DUQvseiHftBEHg+2X0TLLiQJTeC9AiRHd5FVJnPPElYb lxxPqfiAsI1Mgv8I+V376PM9wMvlvyOJ7e70ff17MVg76qQWh9VNmIjZtxOUJvzkC8tnhZSjC1N jzvh7HhbHbPiLW3If1WBwr4m3FGSaLZCkvpEcjqE0BxhKn72316C3isJ692w6ML5aihvNSQd5yG gIiEzMvhAlcPCptimNat07I8XrD3u0pMAbszstnw8IgoCsgI00380osrEUCxlC1DguyrhptPAGY TEtYyb3N1IA3zTsXTzPQthCmGfCxZzbrfeDaKVN8J8Tu7UlXyttSxou8R8CqwzVpWsOa/3gqAks bRp9FyQ4D3FvEXKDX3O9l4SzOQl/oxeFDl6FkWV5CE6qUYfdyKc3Z/PgLrNN8MEiolscqI4xOLz dbS+0BlGierXWEaLCsODvpNSNXGHkO6Tq0W4ag4m3my2mLY7ClV6eHe5wjHtgVpMeCUrqr+QEyW Daonu5qrlLmWVtw== 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