usb 1-1: USB disconnect, device number 2 ================================================================== BUG: KASAN: slab-use-after-free in hdm_disconnect+0xf4/0x18c drivers/most/most_usb.c:1125 Read of size 8 at addr ffff0000c7c098a8 by task kworker/1:4/6542 CPU: 1 UID: 0 PID: 6542 Comm: kworker/1:4 Not tainted 6.15.0-rc5-syzkaller-gc32f8dc5aaf9 #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Workqueue: usb_hub_wq hub_event Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 print_address_description+0xa8/0x254 mm/kasan/report.c:408 print_report+0x68/0x84 mm/kasan/report.c:521 kasan_report+0xb0/0x110 mm/kasan/report.c:634 __asan_report_load8_noabort+0x20/0x2c mm/kasan/report_generic.c:381 hdm_disconnect+0xf4/0x18c drivers/most/most_usb.c:1125 usb_unbind_interface+0x244/0x7c8 drivers/usb/core/driver.c:458 device_rele device_remove drivers/base/dd.c:569 [inline] __device_release_driver drivers/base/dd.c:1272 [inline] device_release_driver_internal+0x3f8/0x658 drivers/base/dd.c:1295 device_release_driver+0x28/0x38 drivers/base/dd.c:1318 bus_remove_device+0x310/0x3b0 drivers/base/bus.c:579 device_del+0x47c/0x808 drivers/base/core.c:3881 usb_disable_device+0x33c/0x780 drivers/usb/core/message.c:1418 usb_disconnect+0x284/0x7f8 drivers/usb/core/hub.c:2316 hub_port_connect drivers/usb/core/hub.c:5371 [inline] hub_port_connect_change drivers/usb/core/hub.c:5671 [inline] port_event drivers/usb/core/hub.c:5831 [inline] hub_event+0x1698/0x3cf0 drivers/usb/core/hub.c:5913 process_one_work+0x7e8/0x156c kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x958/0xed8 kernel/workqueue.c:3400 kthread+0x5fc/0x75c kernel/kthread.c:464 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847 Allocated by task 9: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x40/0x78 mm/kasan/common.c:68 kasan_save_alloc_info+0x44/0x54 mm/kasan/generic.c:562 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0x9c/0xb4 mm/kasan/common.c:394 kasan_kmalloc include/linux/kasan.h:260 [inline] __kmalloc_cache_noprof+0x2a4/0x3fc mm/slub.c:4358 kmalloc_noprof include/linux/slab.h:905 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] hdm_probe+0x9c/0x1044 drivers/most/most_usb.c:959 usb_probe_interface+0x584/0xa44 drivers/usb/core/driver.c:396 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x394/0x910 drivers/base/dd.c:657 __driver_probe_device+0x180/0x2d4 drivers/base/dd.c:799 driver_probe_device+0x78/0x330 drivers/base/dd.c:829 __device_attach_driver+0x290/0x4e0 drivers/base/dd.c:957 bus_for_each_drv+0x220/0x2b4 drivers/base/bus.c:462 __device_attach+0x26c/0x388 drivers/base/dd.c:1029 device_initial_probe+0x24/0x34 drivers/base/dd.c:1078 bus_probe_device+0x178/0x240 drivers/base/bus.c:537 device_add+0x71c/0xa60 drivers/base/core.c:3692 usb_set_configuration+0x1640/0x1bac drivers/usb/core/message.c:2210 usb_generic_driver_probe+0x8c/0x144 drivers/usb/core/generic.c:250 usb_probe_device+0x1a4/0x348 drivers/usb/core/driver.c:291 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x394/0x910 drivers/base/dd.c:657 __driver_probe_device+0x180/0x2d4 drivers/base/dd.c:799 driver_probe_device+0x78/0x330 drivers/base/dd.c:829 __device_attach_driver+0x290/0x4e0 drivers/base/dd.c:957 bus_for_each_drv+0x220/0x2b4 drivers/base/bus.c:462 __device_attach+0x26c/0x388 drivers/base/dd.c:1029 device_initial_probe+0x24/0x34 drivers/base/dd.c:1078 bus_probe_device+0x178/0x240 drivers/base/bus.c:537 device_add+0x71c/0xa60 drivers/base/core.c:3692 usb_new_device+0x7f0/0x1220 drivers/usb/core/hub.c:2663 hub_port_connect drivers/usb/core/hub.c:5531 [inline] hub_port_connect_change drivers/usb/core/hub.c:5671 [inline] port_event drivers/usb/core/hub.c:5831 [inline] hub_event+0x2148/0x3cf0 drivers/usb/core/hub.c:5913 process_one_work+0x7e8/0x156c kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x958/0xed8 kernel/workqueue.c:3400 kthread+0x5fc/0x75c kernel/kthread.c:464 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847 Freed by task 6542: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x40/0x78 mm/kasan/common.c:68 kasan_save_free_info+0x58/0x70 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x68/0x88 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2380 [inline] slab_free mm/slub.c:4642 [inline] kfree+0x17c/0x474 mm/slub.c:4841 release_mdev+0x20/0x30 drivers/most/most_usb.c:932 device_release+0x8c/0x1ac drivers/base/core.c:-1 kobject_cleanup lib/kobject.c:689 [inline] kobject_release lib/kobject.c:720 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x2b0/0x438 lib/kobject.c:737 put_device drivers/base/core.c:3800 [inline] device_unregister+0x3c/0xcc drivers/base/core.c:3923 most_deregister_interface+0x3e0/0x42c drivers/most/core.c:1402 hdm_disconnect+0xdc/0x18c drivers/most/most_usb.c:1123 usb_unbind_interface+0x244/0x7c8 drivers/usb/core/driver.c:458 device_remove drivers/base/dd.c:569 [inline] __device_release_driver drivers/base/dd.c:1272 [inline] device_release_driver_internal+0x3f8/0x658 drivers/base/dd.c:1295 device_release_driver+0x28/0x38 drivers/base/dd.c:1318 bus_remove_device+0x310/0x3b0 drivers/base/bus.c:579 device_del+0x47c/0x808 drivers/base/core.c:3881 usb_disable_device+0x33c/0x780 drivers/usb/core/message.c:1418 usb_disconnect+0x284/0x7f8 drivers/usb/core/hub.c:2316 hub_port_connect drivers/usb/core/hub.c:5371 [inline] hub_port_connect_change drivers/usb/core/hub.c:5671 [inline] port_event drivers/usb/core/hub.c:5831 [inline] hub_event+0x1698/0x3cf0 drivers/usb/core/hub.c:5913 process_one_work+0x7e8/0x156c kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x958/0xed8 kernel/workqueue.c:3400 kthread+0x5fc/0x75c kernel/kthread.c:464 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847 The buggy address belongs to the object at ffff0000c7c08000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 6312 bytes inside of freed 8192-byte region [ffff0000c7c08000, ffff0000c7c0a000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x107c08 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x5ffc00000000040(head|node=0|zone=2|lastcpupid=0x7ff) page_type: f5(slab) raw: 05ffc00000000040 ffff0000c0002280 fffffdffc3224600 0000000000000004 raw: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000 head: 05ffc00000000040 ffff0000c0002280 fffffdffc3224600 0000000000000004 head: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000 head: 05ffc00000000003 fffffdffc31f0201 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000c7c09780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000c7c09800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff0000c7c09880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000c7c09900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000c7c09980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 6542 at lib/refcount.c:28 refcount_warn_saturate+0x154/0x1f8 lib/refcount.c:28 Modules linked in: CPU: 1 UID: 0 PID: 6542 Comm: kworker/1:4 Tainted: G B 6.15.0-rc5-syzkaller-gc32f8dc5aaf9 #0 PREEMPT Tainted: [B]=BAD_PAGE Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Workqueue: usb_hub_wq hub_event pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : refcount_warn_saturate+0x154/0x1f8 lib/refcount.c:28 lr : refcount_warn_saturate+0x154/0x1f8 lib/refcount.c:28 sp : ffff8000a4d17330 x29: ffff8000a4d17330 x28: ffff0000d580e0b0 x27: 1fffe00018f81000 x26: 1fffe00018f81007 x25: dfff800000000000 x24: ffff800092081cf0 x23: 1fffe00018f810a1 x22: ffff0000c7c0803c x21: 0000000000000000 x20: ffff0000c7c08038 x19: ffff800092818000 x18: 1fffe00033871676 x17: 0000000000000000 x16: ffff80008ad1d588 x15: ffff700011e720b4 x14: 1ffff00011e720b4 x13: 0000000000000004 x12: ffffffffffffffff x11: 0000000000100000 x10: 00000000000c3a50 x9 : c63d3980d659a700 x8 : c63d3980d659a700 x7 : 0000000000000001 x6 : 0000000000000001 x5 : ffff8000a4d16c78 x4 : ffff80008f405b40 x3 : ffff8000805456dc x2 : 0000000000000000 x1 : 0000000100000000 x0 : 0000000000000000 Call trace: refcount_warn_saturate+0x154/0x1f8 lib/refcount.c:28 (P) __refcount_sub_and_test include/linux/refcount.h:400 [inline] __refcount_dec_and_test include/linux/refcount.h:432 [inline] refcount_dec_and_test include/linux/refcount.h:450 [inline] kref_put include/linux/kref.h:64 [inline] kobject_put+0x194/0x438 lib/kobject.c:737 put_device+0x28/0x40 drivers/base/core.c:3800 hdm_disconnect+0x174/0x18c drivers/most/most_usb.c:1130 usb_unbind_interface+0x244/0x7c8 drivers/usb/core/driver.c:458 device_remove drivers/base/dd.c:569 [inline] __device_release_driver drivers/base/dd.c:1272 [inline] device_release_driver_internal+0x3f8/0x658 drivers/base/dd.c:1295 device_release_driver+0x28/0x38 drivers/base/dd.c:1318 bus_remove_device+0x310/0x3b0 drivers/base/bus.c:579 device_del+0x47c/0x808 drivers/base/core.c:3881 usb_disable_device+0x33c/0x780 drivers/usb/core/message.c:1418 usb_disconnect+0x284/0x7f8 drivers/usb/core/hub.c:2316 hub_port_connect drivers/usb/core/hub.c:5371 [inline] hub_port_connect_change drivers/usb/core/hub.c:5671 [inline] port_event drivers/usb/core/hub.c:5831 [inline] hub_event+0x1698/0x3cf0 drivers/usb/core/hub.c:5913 process_one_work+0x7e8/0x156c kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x958/0xed8 kernel/workqueue.c:3400 kthread+0x5fc/0x75c kernel/kthread.c:464 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847 irq event stamp: 83401 hardirqs last enabled at (83401): [] raw_spin_rq_unlock_irq kernel/sched/sched.h:1525 [inline] hardirqs last enabled at (83401): [] finish_lock_switch+0xb0/0x1c0 kernel/sched/core.c:5130 hardirqs last disabled at (83400): [] __schedule+0x318/0x28d4 kernel/sched/core.c:6671 softirqs last enabled at (83120): [] softirq_handle_end kernel/softirq.c:425 [inline] softirqs last enabled at (83120): [] handle_softirqs+0xaf8/0xc88 kernel/softirq.c:607 softirqs last disabled at (83111): [] __do_softirq+0x14/0x20 kernel/softirq.c:613 ---[ end trace 0000000000000000 ]---