From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE5F0C2BA15 for ; Sun, 5 Apr 2020 20:13:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9313720672 for ; Sun, 5 Apr 2020 20:13:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=daynix-com.20150623.gappssmtp.com header.i=@daynix-com.20150623.gappssmtp.com header.b="jJyCDymm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727677AbgDEUNY (ORCPT ); Sun, 5 Apr 2020 16:13:24 -0400 Received: from mail-lf1-f66.google.com ([209.85.167.66]:40110 "EHLO mail-lf1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726887AbgDEUNY (ORCPT ); Sun, 5 Apr 2020 16:13:24 -0400 Received: by mail-lf1-f66.google.com with SMTP id j17so10087028lfe.7 for ; Sun, 05 Apr 2020 13:13:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=daynix-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=ZecswmQzcKyJcaA1KVr1PgDOFuDkBa9m5xQm0CMlRfg=; b=jJyCDymm6a4Y4wyhQ19mQrdIHDOuRafStVA1S1Ig6u2VsstNNG+WN5ithcMu/UoDhe CJm6CNrO5du/C461KF08IoNM6ixV+wdPZH8150mM/yVeqUBK51IxAnWz7mKOY839n8aW d7cHEB5htx7FQ8+DMQOGIPAUPdAP2iIaT8fdrFL0ztPZz0GCoILB7X3WnENer2eAJskQ eeo1VWbmuMKB2MUvYRbouX1S5SlVWKrKQ6M6xDtskZYZDXj9EBjSi5jMaCUjXzgkBOze jU3zjVkxzmHp8gl2mo4gFFASzkAJPg2bF21TLTOydSfR8DchzsZcVw7KD93PqUSsu39Y 78tQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=ZecswmQzcKyJcaA1KVr1PgDOFuDkBa9m5xQm0CMlRfg=; b=lvqpQLsD7CeJ+4XW4UGqdo+ZpknT/mJumbMrDmk3MvU8NS5dPBL6wMXTMWdwCBP10u V0XSEL0qwhcXQ3hM23Ir6Yu47K4dI6CNxDgGMuSx6b8BDcCKQuwDFieryaLKn+SHtEXi um0bO21fp/et0xHD2gn01epfEdiWqGMvg+hIuXB4Qwmov7MIBb0MfQ2u0uPeWHjFltgg m7jTx82Qk7jOAi2y454WslQ0SUVpz213QWI3rTaiInfLzDdOr/ECNr0A36LKZVUOc5on IvowRbz17UNhVC1keKXM/mcOFw5yZSm+fen/YIRuqA7N+43kIvOL2BIQLPCYBh0XYDin 4lcw== X-Gm-Message-State: AGi0Pub1QZ1xZTv6StS/I+4pIjoweybnYw1WiGIxO4nY6uzgUx9SFxe9 44DkW6URIryYqYaItDv/mhzzTsmo5UnTdQ== X-Google-Smtp-Source: APiQypIEsOpmUVRbUVIGQF9PTFmAXeRwenTbMDANUZ4VQGITx+F9m6bijBqeMQEHZ9PikkiF90Ex9A== X-Received: by 2002:ac2:4143:: with SMTP id c3mr4585061lfi.131.1586117602906; Sun, 05 Apr 2020 13:13:22 -0700 (PDT) Received: from navi.cosmonova.net.ua ([95.67.24.131]) by smtp.gmail.com with ESMTPSA id m1sm5450815lfl.69.2020.04.05.13.13.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 05 Apr 2020 13:13:22 -0700 (PDT) From: andrew@daynix.com To: virtualization@lists.linux-foundation.org Cc: gregkh@linuxfoundation.org, jslaby@suse.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: [PATCH] Fix: buffer overflow during hvc_alloc(). Date: Sun, 5 Apr 2020 23:40:24 +0300 Message-Id: <20200405204024.1007843-1-andrew@daynix.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andrew Melnychenko If there is a lot(more then 16) of virtio-console devices or virtio_console module is reloaded - buffers 'vtermnos' and 'cons_ops' are overflowed. In older kernels it overruns spinlock which leads to kernel freezing: https://bugzilla.redhat.com/show_bug.cgi?id=1786239 Signed-off-by: Andrew Melnychenko --- drivers/tty/hvc/hvc_console.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c index 27284a2dcd2b..436cc51c92c3 100644 --- a/drivers/tty/hvc/hvc_console.c +++ b/drivers/tty/hvc/hvc_console.c @@ -302,10 +302,6 @@ int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops) vtermnos[index] = vtermno; cons_ops[index] = ops; - /* reserve all indices up to and including this index */ - if (last_hvc < index) - last_hvc = index; - /* check if we need to re-register the kernel console */ hvc_check_console(index); @@ -960,13 +956,22 @@ struct hvc_struct *hvc_alloc(uint32_t vtermno, int data, cons_ops[i] == hp->ops) break; - /* no matching slot, just use a counter */ - if (i >= MAX_NR_HVC_CONSOLES) - i = ++last_hvc; + if (i >= MAX_NR_HVC_CONSOLES) { + + /* find 'empty' slot for console */ + for (i = 0; i < MAX_NR_HVC_CONSOLES && vtermnos[i] != -1; i++) { + } + + /* no matching slot, just use a counter */ + if (i == MAX_NR_HVC_CONSOLES) + i = ++last_hvc + MAX_NR_HVC_CONSOLES; + } hp->index = i; - cons_ops[i] = ops; - vtermnos[i] = vtermno; + if (i < MAX_NR_HVC_CONSOLES) { + cons_ops[i] = ops; + vtermnos[i] = vtermno; + } list_add_tail(&(hp->next), &hvc_structs); mutex_unlock(&hvc_structs_mutex); -- 2.24.1