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=-9.7 required=3.0 tests=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 DC450C2D0F6 for ; Wed, 13 May 2020 02:05:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B1FD320714 for ; Wed, 13 May 2020 02:05:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728440AbgEMCFe (ORCPT ); Tue, 12 May 2020 22:05:34 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:4399 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726885AbgEMCFe (ORCPT ); Tue, 12 May 2020 22:05:34 -0400 Received: from DGGEMS411-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 704C4BFD677722C6A282; Wed, 13 May 2020 10:05:26 +0800 (CST) Received: from huawei.com (10.175.101.78) by DGGEMS411-HUB.china.huawei.com (10.3.19.211) with Microsoft SMTP Server id 14.3.487.0; Wed, 13 May 2020 10:05:16 +0800 From: Yang Yingliang To: CC: , Subject: [PATCH -next] vgacon: Fix an out-of-bounds in vgacon_scrollback_update() Date: Wed, 13 May 2020 10:28:52 +0800 Message-ID: <1589336932-35508-1-git-send-email-yangyingliang@huawei.com> X-Mailer: git-send-email 1.8.3 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.175.101.78] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I got a slab-out-of-bounds report when I doing fuzz test. [ 334.989515] ================================================================== [ 334.989577] BUG: KASAN: slab-out-of-bounds in vgacon_scroll+0x57a/0x8ed [ 334.989588] Write of size 1766 at addr ffff8883de69ff3e by task test/2658 [ 334.989593] [ 334.989608] CPU: 3 PID: 2658 Comm: test Not tainted 5.7.0-rc5-00005-g152036d1379f #789 [ 334.989617] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014 [ 334.989624] Call Trace: [ 334.989646] dump_stack+0xe4/0x14e [ 334.989676] print_address_description.constprop.5+0x3f/0x60 [ 334.989699] ? vgacon_scroll+0x57a/0x8ed [ 334.989710] __kasan_report.cold.8+0x92/0xaf [ 334.989735] ? vgacon_scroll+0x57a/0x8ed [ 334.989761] kasan_report+0x37/0x50 [ 334.989789] check_memory_region+0x1c1/0x1e0 [ 334.989806] memcpy+0x38/0x60 [ 334.989824] vgacon_scroll+0x57a/0x8ed [ 334.989876] con_scroll+0x4ef/0x5e0 [ 334.989904] ? lockdep_hardirqs_on+0x5e0/0x5e0 [ 334.989934] lf+0x24f/0x2a0 [ 334.989951] ? con_scroll+0x5e0/0x5e0 [ 334.989975] ? find_held_lock+0x33/0x1c0 [ 334.990005] do_con_trol+0x313/0x5ff0 [ 334.990027] ? lock_downgrade+0x730/0x730 [ 334.990045] ? reset_palette+0x440/0x440 [ 334.990070] ? _raw_spin_unlock_irqrestore+0x4b/0x60 [ 334.990095] ? notifier_call_chain+0x120/0x170 [ 334.990132] ? __atomic_notifier_call_chain+0xf0/0x180 [ 334.990160] do_con_write.part.16+0xb2b/0x1b20 [ 334.990238] ? do_con_trol+0x5ff0/0x5ff0 [ 334.990258] ? mutex_lock_io_nested+0x1280/0x1280 [ 334.990269] ? rcu_read_unlock+0x50/0x50 [ 334.990315] ? __mutex_unlock_slowpath+0xd9/0x670 [ 334.990340] ? lockdep_hardirqs_on+0x3a2/0x5e0 [ 334.990368] con_write+0x36/0xc0 [ 334.990389] do_output_char+0x561/0x780 [ 334.990414] n_tty_write+0x58e/0xd30 [ 334.990478] ? n_tty_read+0x1800/0x1800 [ 334.990500] ? prepare_to_wait_exclusive+0x300/0x300 [ 334.990525] ? __might_fault+0x17a/0x1c0 [ 334.990557] tty_write+0x430/0x960 [ 334.990568] ? n_tty_read+0x1800/0x1800 [ 334.990600] ? tty_release+0x1280/0x1280 [ 334.990622] __vfs_write+0x81/0x100 [ 334.990648] vfs_write+0x1ce/0x510 [ 334.990676] ksys_write+0x104/0x200 [ 334.990691] ? __ia32_sys_read+0xb0/0xb0 [ 334.990708] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 334.990725] ? trace_hardirqs_off_caller+0x40/0x1a0 [ 334.990744] ? do_syscall_64+0x3b/0x5e0 [ 334.990775] do_syscall_64+0xc8/0x5e0 [ 334.990798] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 334.990811] RIP: 0033:0x44f369 [ 334.990827] Code: 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 [ 334.990834] RSP: 002b:00007ffe9ace0968 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 [ 334.990848] RAX: ffffffffffffffda RBX: 0000000000400418 RCX: 000000000044f369 [ 334.990856] RDX: 0000000000000381 RSI: 0000000020003500 RDI: 0000000000000003 [ 334.990865] RBP: 00007ffe9ace0980 R08: 0000000020003530 R09: 00007ffe9ace0980 [ 334.990873] R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000402110 [ 334.990881] R13: 0000000000000000 R14: 00000000006bf018 R15: 0000000000000000 [ 334.990937] [ 334.990943] The buggy address belongs to the page: [ 334.990962] page:ffffea000f79a400 refcount:1 mapcount:0 mapping:000000002bff47b3 index:0x0 head:ffffea000f79a400 order:4 compound_mapcount:0 compound_pincount:0 [ 334.990973] flags: 0x2fffff80010000(head) [ 334.990992] raw: 002fffff80010000 dead000000000100 dead000000000122 0000000000000000 [ 334.991006] raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000 [ 334.991013] page dumped because: kasan: bad access detected [ 334.991017] [ 334.991023] Memory state around the buggy address: [ 334.991034] ffff8883de6a0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 334.991044] ffff8883de6a0080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 334.991054] >ffff8883de6a0100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc [ 334.991061] ^ [ 334.991071] ffff8883de6a0180: fc fc fc fc fc fc 00 00 00 00 00 00 00 00 00 00 [ 334.991082] ffff8883de6a0200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 334.991088] ================================================================== Because vgacon_scrollback_cur->tail plus memcpy size is greater than vgacon_scrollback_cur->size. Fix this by checking the memcpy size. Reported-by: Hulk Robot Signed-off-by: Yang Yingliang --- drivers/video/console/vgacon.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c index 998b0de1812f..b51ffb9a208d 100644 --- a/drivers/video/console/vgacon.c +++ b/drivers/video/console/vgacon.c @@ -243,6 +243,7 @@ static void vgacon_scrollback_startup(void) static void vgacon_scrollback_update(struct vc_data *c, int t, int count) { void *p; + int size; if (!vgacon_scrollback_cur->data || !vgacon_scrollback_cur->size || c->vc_num != fg_console) @@ -251,13 +252,17 @@ static void vgacon_scrollback_update(struct vc_data *c, int t, int count) p = (void *) (c->vc_origin + t * c->vc_size_row); while (count--) { + size = vgacon_scrollback_cur->size - vgacon_scrollback_cur->tail; + if (size > c->vc_size_row) + size = c->vc_size_row; + scr_memcpyw(vgacon_scrollback_cur->data + vgacon_scrollback_cur->tail, - p, c->vc_size_row); + p, size); vgacon_scrollback_cur->cnt++; - p += c->vc_size_row; - vgacon_scrollback_cur->tail += c->vc_size_row; + p += size; + vgacon_scrollback_cur->tail += size; if (vgacon_scrollback_cur->tail >= vgacon_scrollback_cur->size) vgacon_scrollback_cur->tail = 0; -- 2.17.1