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
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