From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([59.151.112.132]:47191 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751398AbcAVAcL (ORCPT ); Thu, 21 Jan 2016 19:32:11 -0500 Subject: Re: use-after-free in perf_trace_btrfs__work To: Chris Mason , Dave Jones , , , , Linux Kernel References: <20160115030731.GA24109@codemonkey.org.uk> <20160121170615.ttsumvs6esf6t332@floor.thefacebook.com> From: Qu Wenruo Message-ID: <56A17878.50207@cn.fujitsu.com> Date: Fri, 22 Jan 2016 08:31:52 +0800 MIME-Version: 1.0 In-Reply-To: <20160121170615.ttsumvs6esf6t332@floor.thefacebook.com> Content-Type: text/plain; charset="utf-8"; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: Chris Mason wrote on 2016/01/21 12:06 -0500: > On Thu, Jan 14, 2016 at 10:07:31PM -0500, Dave Jones wrote: >> I just hit a bunch of instances of this spew.. >> This is on Linus' tree from a few hours ago >> >> ================================================================== >> BUG: KASAN: use-after-free in perf_trace_btrfs__work+0x1b1/0x2a0 [btrfs] at addr ffff8800b7ea2e60 >> Read of size 8 by task trinity-c14/6745 >> ============================================================================= >> BUG kmalloc-256 (Not tainted): kasan: bad access detected >> ----------------------------------------------------------------------------- >> >> Disabling lock debugging due to kernel taint >> INFO: Allocated in btrfs_wq_submit_bio+0xd1/0x300 [btrfs] age=63 cpu=1 pid=6745 >> ___slab_alloc.constprop.70+0x4de/0x580 >> __slab_alloc.isra.67.constprop.69+0x48/0x80 >> kmem_cache_alloc_trace+0x24c/0x2e0 >> btrfs_wq_submit_bio+0xd1/0x300 [btrfs] >> btrfs_submit_bio_hook+0x118/0x260 [btrfs] >> neigh_sysctl_register+0x201/0x360 >> devinet_sysctl_register+0x73/0xe0 >> inetdev_init+0x119/0x1f0 >> inetdev_event+0x5b3/0x7e0 >> notifier_call_chain+0x4e/0xd0 >> raw_notifier_call_chain+0x16/0x20 >> call_netdevice_notifiers_info+0x3d/0x70 >> register_netdevice+0x62d/0x730 >> register_netdev+0x1a/0x30 >> loopback_net_init+0x5d/0xd0 >> ops_init+0x5b/0x1e0 >> INFO: Freed in run_one_async_free+0x12/0x20 [btrfs] age=177 cpu=1 pid=8018 >> __slab_free+0x19e/0x2d0 >> kfree+0x24e/0x270 >> run_one_async_free+0x12/0x20 [btrfs] >> btrfs_scrubparity_helper+0x38d/0x740 [btrfs] >> btrfs_worker_helper+0xe/0x10 [btrfs] >> process_one_work+0x417/0xa40 >> worker_thread+0x8b/0x730 >> kthread+0x199/0x1c0 >> ret_from_fork+0x3f/0x70 >> INFO: Slab 0xffffea0002dfa800 objects=28 used=28 fp=0x (null) flags=0x4000000000004080 >> INFO: Object 0xffff8800b7ea2da0 @offset=11680 fp=0xffff8800b7ea2480 > > static inline void __btrfs_queue_work(struct __btrfs_workqueue *wq, > struct btrfs_work *work) > { > unsigned long flags; > > work->wq = wq; > thresh_queue_hook(wq); > if (work->ordered_func) { > spin_lock_irqsave(&wq->list_lock, flags); > list_add_tail(&work->ordered_list, &wq->ordered_list); > spin_unlock_irqrestore(&wq->list_lock, flags); > } > queue_work(wq->normal_wq, &work->normal_work); > trace_btrfs_work_queued(work); > } > > Qu, 'work' can be freed before queue_work returns. I don't see any reason > here to have it after the queue_work() call, do you? > > -chris > > Right, trace_btrfs_work_queued() should be called at the very beginning. I'll submit the fix soon. Thanks, Qu