usb 2-1: USB disconnect, device number 39 ================================================================== BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:26 [inline] BUG: KASAN: use-after-free in refcount_inc_not_zero_checked+0x72/0x1e0 lib/refcount.c:123 Read of size 4 at addr ffff8881af673020 by task kworker/1:6/3852 CPU: 1 PID: 3852 Comm: kworker/1:6 Not tainted 5.4.0-rc6-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+0xca/0x13e lib/dump_stack.c:113 print_address_description.constprop.0+0x36/0x50 mm/kasan/report.c:374 __kasan_report.cold+0x1a/0x33 mm/kasan/report.c:506 kasan_report+0xe/0x20 mm/kasan/common.c:634 check_memory_region_inline mm/kasan/generic.c:185 [inline] check_memory_region+0x128/0x190 mm/kasan/generic.c:192 atomic_read include/asm-generic/atomic-instrumented.h:26 [inline] refcount_inc_not_zero_checked+0x72/0x1e0 lib/refcount.c:123 refcount_inc_checked+0x12/0x60 lib/refcount.c:156 get_task_struct include/linux/sched/task.h:110 [inline] kthread_stop+0x6c/0x610 kernel/kthread.c:554 hwrng_unregister+0x190/0x210 drivers/char/hw_random/core.c:538 chaoskey_disconnect+0x1b2/0x200 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+0x2dc/0x4a0 drivers/base/bus.c:532 device_del+0x420/0xb20 drivers/base/core.c:2376 usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237 usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2200 hub_port_connect drivers/usb/core/hub.c:5035 [inline] hub_port_connect_change drivers/usb/core/hub.c:5324 [inline] port_event drivers/usb/core/hub.c:5470 [inline] hub_event+0x16f2/0x3800 drivers/usb/core/hub.c:5552 process_one_work+0x92b/0x1530 kernel/workqueue.c:2269 worker_thread+0x96/0xe20 kernel/workqueue.c:2415 kthread+0x318/0x420 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Allocated by task 14487: save_stack+0x1b/0x80 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] __kasan_kmalloc mm/kasan/common.c:510 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:483 slab_post_alloc_hook mm/slab.h:584 [inline] slab_alloc_node mm/slub.c:2779 [inline] slab_alloc mm/slub.c:2787 [inline] kmem_cache_alloc+0xd8/0x2e0 mm/slub.c:2792 getname_flags fs/namei.c:138 [inline] getname_flags+0xd2/0x5b0 fs/namei.c:128 user_path_at_empty+0x2a/0x50 fs/namei.c:2598 user_path_at include/linux/namei.h:49 [inline] vfs_statx+0x113/0x1e0 fs/stat.c:187 vfs_stat include/linux/fs.h:3242 [inline] __do_sys_newstat+0x96/0x120 fs/stat.c:341 do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 14487: save_stack+0x1b/0x80 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] kasan_set_free_info mm/kasan/common.c:332 [inline] __kasan_slab_free+0x130/0x180 mm/kasan/common.c:471 slab_free_hook mm/slub.c:1424 [inline] slab_free_freelist_hook mm/slub.c:1475 [inline] slab_free mm/slub.c:3025 [inline] kmem_cache_free+0xb9/0x380 mm/slub.c:3041 putname+0xe1/0x120 fs/namei.c:259 filename_lookup+0x28f/0x3f0 fs/namei.c:2347 user_path_at include/linux/namei.h:49 [inline] vfs_statx+0x113/0x1e0 fs/stat.c:187 vfs_stat include/linux/fs.h:3242 [inline] __do_sys_newstat+0x96/0x120 fs/stat.c:341 do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8881af672200 which belongs to the cache names_cache of size 4096 The buggy address is located 3616 bytes inside of 4096-byte region [ffff8881af672200, ffff8881af673200) The buggy address belongs to the page: page:ffffea0006bd9c00 refcount:1 mapcount:0 mapping:ffff8881da11c000 index:0x0 compound_mapcount: 0 flags: 0x200000000010200(slab|head) raw: 0200000000010200 dead000000000100 dead000000000122 ffff8881da11c000 raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8881af672f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881af672f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881af673000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881af673080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881af673100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================