On Wed, Jan 29, 2020 at 1:27 PM syzbot <syzbot+73163a4458e7367880a0@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: cd234325 usb: gadget: add raw-gadget interface > git tree: https://github.com/google/kasan.git usb-fuzzer > console output: https://syzkaller.appspot.com/x/log.txt?x=140e49bee00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=bb745005307bc641 > dashboard link: https://syzkaller.appspot.com/bug?extid=73163a4458e7367880a0 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > Unfortunately, I don't have any reproducer for this crash yet. > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+73163a4458e7367880a0@xxxxxxxxxxxxxxxxxxxxxxxxx > > usb 2-1: USB disconnect, device number 45 > ================================================================== > BUG: KASAN: use-after-free in atomic_fetch_add include/asm-generic/atomic-instrumented.h:111 [inline] > BUG: KASAN: use-after-free in refcount_add include/linux/refcount.h:188 [inline] > BUG: KASAN: use-after-free in refcount_inc include/linux/refcount.h:228 [inline] > BUG: KASAN: use-after-free in get_task_struct include/linux/sched/task.h:113 [inline] > BUG: KASAN: use-after-free in kthread_stop+0x90/0x780 kernel/kthread.c:554 > Write of size 4 at addr ffff8881ca88e220 by task kworker/0:10/18542 > > CPU: 0 PID: 18542 Comm: kworker/0:10 Not tainted 5.5.0-rc7-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Workqueue: usb_hub_wq hub_event > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0xef/0x16e lib/dump_stack.c:118 > print_address_description.constprop.0.cold+0xd3/0x314 mm/kasan/report.c:374 > __kasan_report.cold+0x37/0x85 mm/kasan/report.c:506 > kasan_report+0xe/0x20 mm/kasan/common.c:639 > check_memory_region_inline mm/kasan/generic.c:185 [inline] > check_memory_region+0x152/0x1c0 mm/kasan/generic.c:192 > atomic_fetch_add include/asm-generic/atomic-instrumented.h:111 [inline] > refcount_add include/linux/refcount.h:188 [inline] > refcount_inc include/linux/refcount.h:228 [inline] > get_task_struct include/linux/sched/task.h:113 [inline] > kthread_stop+0x90/0x780 kernel/kthread.c:554 > hwrng_unregister+0x24f/0x330 drivers/char/hw_random/core.c:556 > chaoskey_disconnect+0x216/0x290 drivers/usb/misc/chaoskey.c:232 > usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423 > __device_release_driver drivers/base/dd.c:1134 [inline] > device_release_driver_internal+0x42f/0x500 drivers/base/dd.c:1165 > bus_remove_device+0x2eb/0x5a0 drivers/base/bus.c:532 > device_del+0x481/0xd30 drivers/base/core.c:2664 > usb_disable_device+0x23d/0x790 drivers/usb/core/message.c:1237 > usb_disconnect+0x293/0x900 drivers/usb/core/hub.c:2201 > hub_port_connect drivers/usb/core/hub.c:5036 [inline] > hub_port_connect_change drivers/usb/core/hub.c:5325 [inline] > port_event drivers/usb/core/hub.c:5471 [inline] > hub_event+0x1a1d/0x4300 drivers/usb/core/hub.c:5553 > process_one_work+0x945/0x15c0 kernel/workqueue.c:2264 > worker_thread+0x96/0xe20 kernel/workqueue.c:2410 > kthread+0x318/0x420 kernel/kthread.c:255 > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 > > Allocated by task 1824: > save_stack+0x1b/0x80 mm/kasan/common.c:72 > set_track mm/kasan/common.c:80 [inline] > __kasan_kmalloc mm/kasan/common.c:513 [inline] > __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:486 > slab_post_alloc_hook mm/slab.h:584 [inline] > slab_alloc_node mm/slub.c:2759 [inline] > kmem_cache_alloc_node+0xdc/0x330 mm/slub.c:2795 > alloc_task_struct_node kernel/fork.c:169 [inline] > dup_task_struct kernel/fork.c:868 [inline] > copy_process+0x43e3/0x6710 kernel/fork.c:1911 > _do_fork+0x12d/0xfd0 kernel/fork.c:2421 > __do_sys_clone kernel/fork.c:2576 [inline] > __se_sys_clone kernel/fork.c:2557 [inline] > __x64_sys_clone+0x182/0x210 kernel/fork.c:2557 > do_syscall_64+0xb6/0x5a0 arch/x86/entry/common.c:294 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Freed by task 1824: > save_stack+0x1b/0x80 mm/kasan/common.c:72 > set_track mm/kasan/common.c:80 [inline] > kasan_set_free_info mm/kasan/common.c:335 [inline] > __kasan_slab_free+0x117/0x160 mm/kasan/common.c:474 > slab_free_hook mm/slub.c:1425 [inline] > slab_free_freelist_hook mm/slub.c:1458 [inline] > slab_free mm/slub.c:3005 [inline] > kmem_cache_free+0x9b/0x360 mm/slub.c:3021 > __put_task_struct+0x220/0x510 kernel/fork.c:751 > put_task_struct include/linux/sched/task.h:122 [inline] > delayed_put_task_struct+0x22a/0x370 kernel/exit.c:182 > __rcu_reclaim kernel/rcu/rcu.h:222 [inline] > rcu_do_batch kernel/rcu/tree.c:2183 [inline] > rcu_core+0x664/0x1e10 kernel/rcu/tree.c:2408 > __do_softirq+0x21e/0x950 kernel/softirq.c:292 > > The buggy address belongs to the object at ffff8881ca88e200 > which belongs to the cache task_struct of size 6016 > The buggy address is located 32 bytes inside of > 6016-byte region [ffff8881ca88e200, ffff8881ca88f980) > The buggy address belongs to the page: > page:ffffea00072a2200 refcount:1 mapcount:0 mapping:ffff8881da116000 index:0x0 compound_mapcount: 0 > raw: 0200000000010200 dead000000000100 dead000000000122 ffff8881da116000 > raw: 0000000000000000 0000000000050005 00000001ffffffff 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8881ca88e100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff8881ca88e180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > >ffff8881ca88e200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff8881ca88e280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8881ca88e300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > > > --- > This bug is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > #syz dup: KASAN: use-after-free Read in chaoskey_disconnect https://syzkaller.appspot.com/bug?id=d39d574f73e4b96265c6af6deeaff32f9bbd5ede > syzbot will keep track of this bug report. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
