From patchwork Sat Feb 26 09:53:43 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12761244 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C4E63C433EF for ; Sat, 26 Feb 2022 09:38:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230357AbiBZJiq (ORCPT ); Sat, 26 Feb 2022 04:38:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56694 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230171AbiBZJip (ORCPT ); Sat, 26 Feb 2022 04:38:45 -0500 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CED17AA2FB; Sat, 26 Feb 2022 01:38:10 -0800 (PST) Received: from kwepemi100018.china.huawei.com (unknown [172.30.72.53]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4K5M1B6S4sz9sG0; Sat, 26 Feb 2022 17:34:38 +0800 (CST) Received: from kwepemm600009.china.huawei.com (7.193.23.164) by kwepemi100018.china.huawei.com (7.221.188.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Sat, 26 Feb 2022 17:38:08 +0800 Received: from huawei.com (10.175.127.227) by kwepemm600009.china.huawei.com (7.193.23.164) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Sat, 26 Feb 2022 17:38:07 +0800 From: Yu Kuai To: , , , CC: , , , Subject: [PATCH] blktrace: Revert "blktrace: remove debugfs file dentries from struct blk_trace" Date: Sat, 26 Feb 2022 17:53:43 +0800 Message-ID: <20220226095343.1121256-1-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemm600009.china.huawei.com (7.193.23.164) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org This reverts commit c0ea57608b691d6cde8aff23e11f9858a86b5918. When tracing the whole disk, 'dropped' and 'msg' will be created under 'q->debugfs_dir' and 'bt->dir' is NULL, thus blk_trace_free() won't remove those files. What's worse, the following UAF can be triggered because of stale 'dropped' and 'msg': ================================================================== BUG: KASAN: use-after-free in blk_dropped_read+0x89/0x100 Read of size 4 at addr ffff88816912f3d8 by task blktrace/1188 CPU: 27 PID: 1188 Comm: blktrace Not tainted 5.17.0-rc4-next-20220217+ #469 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-4 Call Trace: dump_stack_lvl+0x34/0x44 print_address_description.constprop.0.cold+0xab/0x381 ? blk_dropped_read+0x89/0x100 ? blk_dropped_read+0x89/0x100 kasan_report.cold+0x83/0xdf ? blk_dropped_read+0x89/0x100 kasan_check_range+0x140/0x1b0 blk_dropped_read+0x89/0x100 ? blk_create_buf_file_callback+0x20/0x20 ? kmem_cache_free+0xa1/0x500 ? do_sys_openat2+0x258/0x460 full_proxy_read+0x8f/0xc0 vfs_read+0xc6/0x260 ksys_read+0xb9/0x150 ? vfs_write+0x3d0/0x3d0 ? fpregs_assert_state_consistent+0x55/0x60 ? exit_to_user_mode_prepare+0x39/0x1e0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fbc080d92fd Code: ce 20 00 00 75 10 b8 00 00 00 00 0f 05 48 3d 01 f0 ff ff 73 31 c3 48 83 1 RSP: 002b:00007fbb95ff9cb0 EFLAGS: 00000293 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007fbb95ff9dc0 RCX: 00007fbc080d92fd RDX: 0000000000000100 RSI: 00007fbb95ff9cc0 RDI: 0000000000000045 RBP: 0000000000000045 R08: 0000000000406299 R09: 00000000fffffffd R10: 000000000153afa0 R11: 0000000000000293 R12: 00007fbb780008c0 R13: 00007fbb78000938 R14: 0000000000608b30 R15: 00007fbb780029c8 Allocated by task 1050: kasan_save_stack+0x1e/0x40 __kasan_kmalloc+0x81/0xa0 do_blk_trace_setup+0xcb/0x410 __blk_trace_setup+0xac/0x130 blk_trace_ioctl+0xe9/0x1c0 blkdev_ioctl+0xf1/0x390 __x64_sys_ioctl+0xa5/0xe0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae Freed by task 1050: kasan_save_stack+0x1e/0x40 kasan_set_track+0x21/0x30 kasan_set_free_info+0x20/0x30 __kasan_slab_free+0x103/0x180 kfree+0x9a/0x4c0 __blk_trace_remove+0x53/0x70 blk_trace_ioctl+0x199/0x1c0 blkdev_common_ioctl+0x5e9/0xb30 blkdev_ioctl+0x1a5/0x390 __x64_sys_ioctl+0xa5/0xe0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff88816912f380 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 88 bytes inside of 96-byte region [ffff88816912f380, ffff88816912f3e0) The buggy address belongs to the page: page:000000009a1b4e7c refcount:1 mapcount:0 mapping:0000000000000000 index:0x0f flags: 0x17ffffc0000200(slab|node=0|zone=2|lastcpupid=0x1fffff) raw: 0017ffffc0000200 ffffea00044f1100 dead000000000002 ffff88810004c780 raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88816912f280: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff88816912f300: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc >ffff88816912f380: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff88816912f400: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff88816912f480: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ================================================================== Fixes: c0ea57608b69 ("blktrace: remove debugfs file dentries from struct blk_trace") Signed-off-by: Yu Kuai --- include/linux/blktrace_api.h | 2 ++ kernel/trace/blktrace.c | 8 ++++++-- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h index 22501a293fa5..f288d229727c 100644 --- a/include/linux/blktrace_api.h +++ b/include/linux/blktrace_api.h @@ -23,6 +23,8 @@ struct blk_trace { u32 pid; u32 dev; struct dentry *dir; + struct dentry *dropped_file; + struct dentry *msg_file; struct list_head running_list; atomic_t dropped; }; diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c index 19514edc44f7..13152a17fdb3 100644 --- a/kernel/trace/blktrace.c +++ b/kernel/trace/blktrace.c @@ -312,6 +312,8 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, static void blk_trace_free(struct blk_trace *bt) { + debugfs_remove(bt->msg_file); + debugfs_remove(bt->dropped_file); relay_close(bt->rchan); debugfs_remove(bt->dir); free_percpu(bt->sequence); @@ -543,8 +545,10 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev, INIT_LIST_HEAD(&bt->running_list); ret = -EIO; - debugfs_create_file("dropped", 0444, dir, bt, &blk_dropped_fops); - debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops); + bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt, + &blk_dropped_fops); + + bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops); bt->rchan = relay_open("trace", dir, buts->buf_size, buts->buf_nr, &blk_relay_callbacks, bt);