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=0xffff8800b7ea2480static 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
