usb 1-1: USB disconnect, device number 25 ================================================================== BUG: KASAN: slab-use-after-free in hdm_disconnect+0xf4/0x18c drivers/most/most_usb.c:1125 Read of size 8 at addr ffff0000d761d8b0 by task kworker/0:2/1857 CPU: 0 UID: 0 PID: 1857 Comm: kworker/0:2 Not tainted syzkaller #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025 Workqueue: usb_hub_wq hub_event Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 print_address_description+0xa8/0x238 mm/kasan/report.c:378 print_report+0x68/0x84 mm/kasan/report.c:482 kasan_report+0xb0/0x110 mm/kasan/report.c:595 __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+0x244/0x7e4 drivers/usb/core/driver.c:458 device_remove drivers/base/dd.c:571 [inline] __device_release_driver drivers/base/dd.c:1274 [inline] device_release_driver_internal+0x3f8/0x68c drivers/base/dd.c:1297 device_release_driver+0x28/0x38 drivers/base/dd.c:1320 bus_remove_device+0x310/0x3b0 drivers/base/bus.c:579 device_del+0x47c/0x808 drivers/base/core.c:3878 usb_disable_device+0x33c/0x780 drivers/usb/core/message.c:1418 usb_disconnect+0x284/0x82c drivers/usb/core/hub.c:2344 hub_port_connect drivers/usb/core/hub.c:5406 [inline] hub_port_connect_change drivers/usb/core/hub.c:5706 [inline] port_event drivers/usb/core/hub.c:5870 [inline] hub_event+0x1688/0x3c78 drivers/usb/core/hub.c:5952 process_one_work+0x7e8/0x155c kernel/workqueue.c:3263 process_scheduled_works kernel/workqueue.c:3346 [inline] worker_thread+0x990/0xed8 kernel/workqueue.c:3427 kthread+0x5fc/0x75c kernel/kthread.c:463 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844 Allocated by task 1857: kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x40/0x78 mm/kasan/common.c:77 kasan_save_alloc_info+0x44/0x54 mm/kasan/generic.c:573 poison_kmalloc_redzone mm/kasan/common.c:400 [inline] __kasan_kmalloc+0x9c/0xb4 mm/kasan/common.c:417 kasan_kmalloc include/linux/kasan.h:262 [inline] __kmalloc_cache_noprof+0x3a4/0x65c mm/slub.c:5748 kmalloc_noprof include/linux/slab.h:957 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] hdm_probe+0x9c/0x1044 drivers/most/most_usb.c:959 usb_probe_interface+0x5a4/0xaac drivers/usb/core/driver.c:396 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x3b4/0x944 drivers/base/dd.c:659 __driver_probe_device+0x180/0x2d4 drivers/base/dd.c:801 driver_probe_device+0x78/0x330 drivers/base/dd.c:831 __device_attach_driver+0x290/0x4e0 drivers/base/dd.c:959 bus_for_each_drv+0x220/0x2b4 drivers/base/bus.c:462 __device_attach+0x26c/0x388 drivers/base/dd.c:1031 device_initial_probe+0x24/0x34 drivers/base/dd.c:1080 bus_probe_device+0x178/0x240 drivers/base/bus.c:537 device_add+0x71c/0xa60 drivers/base/core.c:3689 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+0x3b4/0x944 drivers/base/dd.c:659 __driver_probe_device+0x180/0x2d4 drivers/base/dd.c:801 driver_probe_device+0x78/0x330 drivers/base/dd.c:831 __device_attach_driver+0x290/0x4e0 drivers/base/dd.c:959 bus_for_each_drv+0x220/0x2b4 drivers/base/bus.c:462 __device_attach+0x26c/0x388 drivers/base/dd.c:1031 device_initial_probe+0x24/0x34 drivers/base/dd.c:1080 bus_probe_device+0x178/0x240 drivers/base/bus.c:537 device_add+0x71c/0xa60 drivers/base/core.c:3689 usb_new_device+0x7f0/0x123c drivers/usb/core/hub.c:2694 hub_port_connect drivers/usb/core/hub.c:5566 [inline] hub_port_connect_change drivers/usb/core/hub.c:5706 [inline] port_event drivers/usb/core/hub.c:5870 [inline] hub_event+0x211c/0x3c78 drivers/usb/core/hub.c:5952 process_one_work+0x7e8/0x155c kernel/workqueue.c:3263 process_scheduled_works kernel/workqueue.c:3346 [inline] worker_thread+0x990/0xed8 kernel/workqueue.c:3427 kthread+0x5fc/0x75c kernel/kthread.c:463 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844 Freed by task 1857: kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x40/0x78 mm/kasan/common.c:77 __kasan_save_free_info+0x58/0x70 mm/kasan/generic.c:587 kasan_save_free_info mm/kasan/kasan.h:406 [inline] poison_slab_object mm/kasan/common.c:252 [inline] __kasan_slab_free+0x74/0xa4 mm/kasan/common.c:284 kasan_slab_free include/linux/kasan.h:234 [inline] slab_free_hook mm/slub.c:2523 [inline] slab_free mm/slub.c:6611 [inline] kfree+0x184/0x600 mm/slub.c:6818 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:3797 [inline] device_unregister+0x3c/0xcc drivers/base/core.c:3920 most_deregister_interface+0x3e0/0x42c drivers/most/core.c:1402 hdm_disconnect+0xdc/0x18c drivers/most/most_usb.c:1123 usb_unbind_interface+0x244/0x7e4 drivers/usb/core/driver.c:458 device_remove drivers/base/dd.c:571 [inline] __device_release_driver drivers/base/dd.c:1274 [inline] device_release_driver_internal+0x3f8/0x68c drivers/base/dd.c:1297 device_release_driver+0x28/0x38 drivers/base/dd.c:1320 bus_remove_device+0x310/0x3b0 drivers/base/bus.c:579 device_del+0x47c/0x808 drivers/base/core.c:3878 usb_disable_device+0x33c/0x780 drivers/usb/core/message.c:1418 usb_disconnect+0x284/0x82c drivers/usb/core/hub.c:2344 hub_port_connect drivers/usb/core/hub.c:5406 [inline] hub_port_connect_change drivers/usb/core/hub.c:5706 [inline] port_event drivers/usb/core/hub.c:5870 [inline] hub_event+0x1688/0x3c78 drivers/usb/core/hub.c:5952 process_one_work+0x7e8/0x155c kernel/workqueue.c:3263 process_scheduled_works kernel/workqueue.c:3346 [inline] worker_thread+0x990/0xed8 kernel/workqueue.c:3427 kthread+0x5fc/0x75c kernel/kthread.c:463 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844 The buggy address belongs to the object at ffff0000d761c000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 6320 bytes inside of freed 8192-byte region [ffff0000d761c000, ffff0000d761e000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x117618 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 anon flags: 0x5ffc00000000040(head|node=0|zone=2|lastcpupid=0x7ff) page_type: f5(slab) raw: 05ffc00000000040 ffff0000c0002280 fffffdffc358dc00 0000000000000005 raw: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000 head: 05ffc00000000040 ffff0000c0002280 fffffdffc358dc00 0000000000000005 head: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000 head: 05ffc00000000003 fffffdffc35d8601 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000d761d780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000d761d800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff0000d761d880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000d761d900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000d761d980: 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: 0 PID: 1857 at lib/refcount.c:28 refcount_warn_saturate+0x154/0x1f8 lib/refcount.c:28 Modules linked in: CPU: 0 UID: 0 PID: 1857 Comm: kworker/0:2 Tainted: G B syzkaller #0 PREEMPT Tainted: [B]=BAD_PAGE Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025 Workqueue: usb_hub_wq hub_event pstate: 63400005 (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 : ffff80009ff17350 x29: ffff80009ff17350 x28: ffff0000ccb180b0 x27: 1fffe0001aec3800 x26: 1fffe0001aec3807 x25: dfff800000000000 x24: ffff80009243c9b0 x23: 1fffe0001aec38a2 x22: ffff0000d761c03c x21: 0000000000000000 x20: ffff0000d761c038 x19: ffff800092bfa000 x18: 1fffe000337db690 x17: 3d3d3d3d3d3d3d3d x16: ffff800082de9540 x15: 0000000000000001 x14: 1ffff00013fe2da0 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000100000 x10: 0000000000052ef4 x9 : 126d4477faf57e00 x8 : 126d4477faf57e00 x7 : 0000000000000001 x6 : ffff8000805638d4 x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000002 x2 : 0000000000000002 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:3797 hdm_disconnect+0x174/0x18c drivers/most/most_usb.c:1130 usb_unbind_interface+0x244/0x7e4 drivers/usb/core/driver.c:458 device_remove drivers/base/dd.c:571 [inline] __device_release_driver drivers/base/dd.c:1274 [inline] device_release_driver_internal+0x3f8/0x68c drivers/base/dd.c:1297 device_release_driver+0x28/0x38 drivers/base/dd.c:1320 bus_remove_device+0x310/0x3b0 drivers/base/bus.c:579 device_del+0x47c/0x808 drivers/base/core.c:3878 usb_disable_device+0x33c/0x780 drivers/usb/core/message.c:1418 usb_disconnect+0x284/0x82c drivers/usb/core/hub.c:2344 hub_port_connect drivers/usb/core/hub.c:5406 [inline] hub_port_connect_change drivers/usb/core/hub.c:5706 [inline] port_event drivers/usb/core/hub.c:5870 [inline] hub_event+0x1688/0x3c78 drivers/usb/core/hub.c:5952 process_one_work+0x7e8/0x155c kernel/workqueue.c:3263 process_scheduled_works kernel/workqueue.c:3346 [inline] worker_thread+0x990/0xed8 kernel/workqueue.c:3427 kthread+0x5fc/0x75c kernel/kthread.c:463 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844 irq event stamp: 151951 hardirqs last enabled at (151951): [] irqentry_exit+0xd8/0x108 kernel/entry/common.c:214 hardirqs last disabled at (151950): [] __enter_from_kernel_mode arch/arm64/kernel/entry-common.c:43 [inline] hardirqs last disabled at (151950): [] enter_from_kernel_mode+0x14/0x34 arch/arm64/kernel/entry-common.c:50 softirqs last enabled at (150580): [] softirq_handle_end kernel/softirq.c:468 [inline] softirqs last enabled at (150580): [] handle_softirqs+0xaf8/0xc88 kernel/softirq.c:650 softirqs last disabled at (150551): [] __do_softirq+0x14/0x20 kernel/softirq.c:656 ---[ end trace 0000000000000000 ]---