From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-97.freemail.mail.aliyun.com (out30-97.freemail.mail.aliyun.com [115.124.30.97]) (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 283D13B0581; Fri, 21 Aug 2026 07:40:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.97 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787298022; cv=none; b=W6CuOcK8Vdy3An0LtAViL8/9awziiTM6EGdVI58XBblu2rOhgFoqohyo1+cJHmji83/qaQ4XDMKKOtDrkHXazsjj3ksoD6pzxnS4cuvmvX4kgCks2NHqkwPk0Cs9qReIqpJfXAcvSwAdKUSrjFlMUqLPsWH+uNcoz0MoIwDL54w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787298022; c=relaxed/simple; bh=BIK6FeWGas+vOHc8L+lchqILJVeY4cgbq0l6axetMb8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: Content-Type:MIME-Version; b=n1Z23CrRFoRIeowq68+YDnCTtWUb8nyrU4NmqUzC75qcdUHiwz6k3Ux4MIjCKnmavFgbtl0XQfKCXzZP0bF1i0H2SxtFeaLQTdlAAjGbsU9nxrGd4DVocFS4ko9aNndYl9Pbt27Ydnj0tnjPWB0VwyMkMlgx+jo72yRfW8kecKI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=Uws0H671; arc=none smtp.client-ip=115.124.30.97 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="Uws0H671" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1787298005; h=From:To:Subject:Date:Message-ID:Content-Type:MIME-Version; bh=pO5YMZPN5pZKeHNfvKxyxBg1SvNVSdVz7HEdqpp7/L4=; b=Uws0H671cJ/pBPsW8bKS0KraUe7NlohgPxxtk6odby/vb1hBLpmO6NbWptLMnPTcyiCHPqPUwMuAuYOaiob4+cOrf3TYHED/vZiNkXkUrjJ0RyjTVk40ec1HYoKF10MOgXP1y5k2S11RfBo11buIHVifRxt3NQ4d595lz3qcfR8= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R171e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037033178;MF=chuyf26@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0X9Lf98I_1787298004; Received: from x31j07255.sqa.na131(mailfrom:Chuyf26@linux.alibaba.com fp:SMTPD_---0X9Lf98I_1787298004 cluster:ay36) by smtp.aliyun-inc.com; Fri, 21 Aug 2026 15:40:05 +0800 From: Chuyf26 To: pabeni@redhat.com Cc: alibuda@linux.alibaba.com, dust.li@linux.ibm.com, sidraya@linux.ibm.com, mjambigi@linux.ibm.com, tonylu@linux.alibaba.com, guwen@linux.alibaba.com, netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org Subject: [PATCH v3] net/smc: release the internal TCP sock on IPPROTO_SMC socket creation failure Date: Fri, 21 Aug 2026 15:38:23 +0800 Message-ID: <178729790329.223882.15209084993558811810@linux.alibaba.com> In-Reply-To: <20260820111229.153086-1-pabeni@redhat.com> References: <20260813060456.b48HqF9m6NTfFXvq_PL9w_Ih493OogqAqxfAHAfU74A@z> <20260820111229.153086-1-pabeni@redhat.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 IPPROTO_SMC sockets create an internal TCP sock ("clcsock") from the proto->init hook. When socket creation fails after proto->init has run - e.g. a cgroup BPF program attached to BPF_CGROUP_INET_SOCK_CREATE denies the socket - sk_common_release() only invokes sk_prot->destroy if it is set, but neither smc_inet_prot nor smc_inet6_prot defines it, and smc_destruct() returns early unless sk_state is SMC_CLOSED. As a result, every failing socket(AF_INET, SOCK_STREAM, IPPROTO_SMC) call leaks one tcp_sock, so an unprivileged task able to attach a deny-all BPF_CGROUP_INET_SOCK_CREATE program to its own cgroup can grow kernel memory unboundedly. Add a .destroy hook to both protos that releases the clcsock via smc_clcsock_release(). smc_sk_init() hashes the sock into the smc hashinfo before the clcsock is created, and smc_diag dumps walk that hash dereferencing smc->clcsock without taking clcsock_release_lock, while sk_common_release() calls .destroy before .unhash. Unhash the sock before releasing the clcsock, as __smc_release() does, so a concurrent dump cannot observe the release; the second unhash in sk_common_release() is a no-op. Fixes: d25a92ccae6b ("net/smc: Introduce IPPROTO_SMC") Reported-by: Abaci Assisted-by: abaci:qwen3.8-max Signed-off-by: Chuyf26 --- Changes since v2 (answering the review): - dropped the smc->clcsock = NULL store: sk_alloc() zeroes the sock (__GFP_ZERO / sk_prot_clear_nulls()), so it is already NULL. The mutex concern does not apply either: .destroy only runs after smc_sk_init() initialized clcsock_release_lock. - unhash the sock before releasing the clcsock in .destroy so a concurrent smc_diag dump cannot observe the release (sk_common_release() calls .destroy before .unhash); the second unhash is a no-op. Tested on a KASAN+SMC_DIAG kernel: the v2 version hits a KASAN report in __smc_diag_dump() when a diag dump races with failing IPPROTO_SMC socket creation, v3 stays clean under the same stress. net/smc/smc_inet.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/net/smc/smc_inet.c b/net/smc/smc_inet.c index a94084b4a498..520b666fdd8f 100644 --- a/net/smc/smc_inet.c +++ b/net/smc/smc_inet.c @@ -15,13 +15,16 @@ #include "smc_inet.h" #include "smc.h" +#include "smc_close.h" static int smc_inet_init_sock(struct sock *sk); +static void smc_inet_destroy_sock(struct sock *sk); static struct proto smc_inet_prot = { .name = "INET_SMC", .owner = THIS_MODULE, .init = smc_inet_init_sock, + .destroy = smc_inet_destroy_sock, .hash = smc_hash_sk, .unhash = smc_unhash_sk, .release_cb = smc_release_cb, @@ -68,6 +71,7 @@ static struct proto smc_inet6_prot = { .name = "INET6_SMC", .owner = THIS_MODULE, .init = smc_inet_init_sock, + .destroy = smc_inet_destroy_sock, .hash = smc_hash_sk, .unhash = smc_unhash_sk, .release_cb = smc_release_cb, @@ -116,6 +120,18 @@ static int smc_inet_init_sock(struct sock *sk) return smc_create_clcsk(net, sk, sk->sk_family); } +static void smc_inet_destroy_sock(struct sock *sk) +{ + /* The sock is hashed and smc_diag dumps dereference smc->clcsock + * without clcsock_release_lock, while sk_common_release() calls + * .destroy before .unhash. Unhash first, as __smc_release() does, + * so no dump can observe the clcsock being released; the second + * unhash is a no-op. + */ + sk->sk_prot->unhash(sk); + smc_clcsock_release(smc_sk(sk)); +} + int __init smc_inet_init(void) { int rc; -- 2.43.5