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 8303643F089; Mon, 17 Aug 2026 14:54:37 +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=1786978481; cv=none; b=tmPjmtFiLar3KVV543e8X1WEK8Aw/ZlYwhddAKovkFCsjDnzTTRW3DuGDoKlbw+AMDDRY4tTJOcDYgXm9ECb5A8QdFQXrfBzqduc6V9FKLjSrRwTHqOZOFRTeLhGk3NR7PKEdXT5cPwIdrUOmVe4rTmkxrR89h3YXgdbxSrz9fQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786978481; c=relaxed/simple; bh=NFPqUCWOm4qQyyd9SuC/KHhmiLxN+zynDEXqhkdY+fI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Fwi82gPIYw5SAJs1IE7zd9YiYGGd8u5mPM8pmvc0TKUNc36uYDIauVcvTRNySm3O7M8ftv9aQB00GHItIq0TKIT+ihCnMk6guaz2Ig198NXQL2KPiHYZKgsN9b3relJgfdUwUb/rVArQn7UPWZO+GKSCH8Dimd+NMP1PnySTm5A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ZsbMQpYK; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ZsbMQpYK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D4AA41F00A3D; Mon, 17 Aug 2026 14:54:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786978476; bh=CdgdFbil1zpqeWLFU8NgAlMh5rS+MyxNwqRsrqbd7i0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ZsbMQpYKb5/Ns7t/PeQGfHLh86Jx4SG8spI7hmCG5DJ/VFzZWgA/lFiZK0PvAL9yp qtfBOgNsvaXoWpWvYRZ+7ZUWsU+cvo17NhtGINd7/8BQggH7m3RmT3dhbZ4TxVQIXB Hrolgf6NdtDeanoXmHEHVaWwxOrbdNEhHLBfF/hM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mahanta Jambigi , Sidraya Jayagond , Breno Leitao , Dust Li , Paolo Abeni , Sasha Levin Subject: [PATCH 6.6 051/156] net/smc: fix TOCTOU race between smc_listen_out() and listener close Date: Mon, 17 Aug 2026 15:33:05 +0200 Message-ID: <20260817132536.589861327@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132534.666299318@linuxfoundation.org> References: <20260817132534.666299318@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sidraya Jayagond [ Upstream commit 185a4caeecabc150106deda1da170b09f2ad803f ] smc_listen_out() reads lsmc->sk.sk_state without the listener lock, then acquires lock_sock_nested() only after the check passes. This opens a window where smc_close_active() can transition the listener to SMC_CLOSED, call smc_close_cleanup_listen() to drain the accept queue, and release the lock, all between the lockless read and the delayed lock acquisition: smc_listen_work (smc_hs_wq) smc_close_active() ------------------------------- ------------------------- release_sock(child) if (sk_state == SMC_LISTEN) TRUE lock_sock(listener) sk_state = SMC_CLOSED smc_close_cleanup_listen() release_sock(listener) flush_work(tcp_listen_work) lock_sock_nested(listener) smc_accept_enqueue(listener, child) /* child enqueued on dead listener */ smc_close_active() flushes only tcp_listen_work. Work items already dispatched onto smc_hs_wq for the CLC handshake continue running unguarded. smc_accept_enqueue() takes a sock_hold() on the child that is never released, so the child smc_sock, its clcsock, and the reference all leak. A remote peer that opens TCP connections while the server calls close() can exhaust kernel memory. Move lock_sock_nested() to before the sk_state check so that the test and the enqueue are atomic under the listener lock. Fixes: fd57770dd198 ("net/smc: wait for pending work before clcsock release_sock") Reviewed-by: Mahanta Jambigi Signed-off-by: Sidraya Jayagond Reviewed-by: Breno Leitao Reviewed-by: Dust Li Link: https://patch.msgid.link/20260803070701.126339-1-sidraya@linux.ibm.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/smc/af_smc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c index e5e07160e5719..087102ff3c640 100644 --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -1921,11 +1921,12 @@ static void smc_listen_out(struct smc_sock *new_smc) atomic_dec(&lsmc->queued_smc_hs); release_sock(newsmcsk); /* lock in smc_listen_work() */ + lock_sock_nested(&lsmc->sk, SINGLE_DEPTH_NESTING); if (lsmc->sk.sk_state == SMC_LISTEN) { - lock_sock_nested(&lsmc->sk, SINGLE_DEPTH_NESTING); smc_accept_enqueue(&lsmc->sk, newsmcsk); release_sock(&lsmc->sk); } else { /* no longer listening */ + release_sock(&lsmc->sk); smc_close_non_accepted(newsmcsk); } -- 2.53.0