usb 1-1: Product: syz usb 1-1: Manufacturer: syz usb 1-1: SerialNumber: syz usb 1-1: USB disconnect, device number 3 ================================================================== BUG: KASAN: use-after-free in hdm_disconnect+0xf4/0x18c drivers/most/most_usb.c:1125 Read of size 8 at addr ffff0000c35dd8b0 by task kworker/1:9/4438 CPU: 1 PID: 4438 Comm: kworker/1:9 Not tainted 6.1.147-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/18/2025 Workqueue: usb_hub_wq hub_event Call trace: dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106 print_address_description+0x88/0x200 mm/kasan/report.c:316 print_report+0x50/0x68 mm/kasan/report.c:418 kasan_report+0xa8/0x100 mm/kasan/report.c:522 __asan_report_load8_noabort+0x2c/0x38 mm/kasan/report_generic.c:351 hdm_disconnect+0xf4/0x18c drivers/most/most_usb.c:1125 usb_unbind_interface+0x1b8/0x750 drivers/usb/core/driver.c:458 device_remove drivers/base/dd.c:550 [inline] __device_release_driver drivers/base/dd.c:1260 [inline] device_release_driver_internal+0x424/0x6d0 drivers/base/dd.c:1286 device_release_driver+0x28/0x38 drivers/base/dd.c:1309 bus_remove_device+0x294/0x388 drivers/base/bus.c:531 device_del+0x568/0x96c drivers/base/core.c:3885 usb_disable_device+0x33c/0x780 drivers/usb/core/message.c:1414 usb_disconnect+0x284/0x790 drivers/usb/core/hub.c:2314 hub_port_connect drivers/usb/core/hub.c:5361 [inline] hub_port_connect_change drivers/usb/core/hub.c:5657 [inline] port_event drivers/usb/core/hub.c:5817 [inline] hub_event+0x1644/0x3e2c drivers/usb/core/hub.c:5899 process_one_work+0x7f4/0x13a8 kernel/workqueue.c:2292 process_scheduled_works kernel/workqueue.c:2355 [inline] worker_thread+0xb30/0xfbc kernel/workqueue.c:2441 kthread+0x250/0x2d8 kernel/kthread.c:376 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:849 Allocated by task 4438: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4c/0x80 mm/kasan/common.c:52 kasan_save_alloc_info+0x28/0x34 mm/kasan/generic.c:505 ____kasan_kmalloc mm/kasan/common.c:374 [inline] __kasan_kmalloc+0xa0/0xb8 mm/kasan/common.c:383 kasan_kmalloc include/linux/kasan.h:211 [inline] kmalloc_trace+0x7c/0x94 mm/slab_common.c:1031 kmalloc include/linux/slab.h:563 [inline] kzalloc include/linux/slab.h:699 [inline] hdm_probe+0x9c/0x1044 drivers/most/most_usb.c:959 usb_probe_interface+0x4fc/0x994 drivers/usb/core/driver.c:396 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x39c/0xae0 drivers/base/dd.c:639 __driver_probe_device+0x180/0x314 drivers/base/dd.c:785 driver_probe_device+0x78/0x330 drivers/base/dd.c:815 __device_attach_driver+0x290/0x4e0 drivers/base/dd.c:943 bus_for_each_drv+0x150/0x1d8 drivers/base/bus.c:429 __device_attach+0x2a8/0x3d4 drivers/base/dd.c:1015 device_initial_probe+0x24/0x34 drivers/base/dd.c:1064 bus_probe_device+0xbc/0x1c4 drivers/base/bus.c:489 device_add+0xb04/0xf94 drivers/base/core.c:3697 usb_set_configuration+0x1598/0x1b0c drivers/usb/core/message.c:2165 usb_generic_driver_probe+0x8c/0x144 drivers/usb/core/generic.c:238 usb_probe_device+0x120/0x25c drivers/usb/core/driver.c:293 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x39c/0xae0 drivers/base/dd.c:639 __driver_probe_device+0x180/0x314 drivers/base/dd.c:785 driver_probe_device+0x78/0x330 drivers/base/dd.c:815 __device_attach_driver+0x290/0x4e0 drivers/base/dd.c:943 bus_for_each_drv+0x150/0x1d8 drivers/base/bus.c:429 __device_attach+0x2a8/0x3d4 drivers/base/dd.c:1015 device_initial_probe+0x24/0x34 drivers/base/dd.c:1064 bus_probe_device+0xbc/0x1c4 drivers/base/bus.c:489 device_add+0xb04/0xf94 drivers/base/core.c:3697 usb_new_device+0x7f0/0x11c4 drivers/usb/core/hub.c:2659 hub_port_connect drivers/usb/core/hub.c:5517 [inline] hub_port_connect_change drivers/usb/core/hub.c:5657 [inline] port_event drivers/usb/core/hub.c:5817 [inline] hub_event+0x221c/0x3e2c drivers/usb/core/hub.c:5899 process_one_work+0x7f4/0x13a8 kernel/workqueue.c:2292 worker_thread+0x8c8/0xfbc kernel/workqueue.c:2439 kthread+0x250/0x2d8 kernel/kthread.c:376 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:849 Freed by task 4438: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4c/0x80 mm/kasan/common.c:52 kasan_save_free_info+0x3c/0x60 mm/kasan/generic.c:516 ____kasan_slab_free+0x148/0x1b0 mm/kasan/common.c:236 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:244 kasan_slab_free include/linux/kasan.h:177 [inline] slab_free_hook mm/slub.c:1724 [inline] slab_free_freelist_hook+0x16c/0x1ec mm/slub.c:1750 slab_free mm/slub.c:3661 [inline] __kmem_cache_free+0xc0/0x224 mm/slub.c:3674 kfree+0xd0/0x1ac mm/slab_common.c:988 release_mdev+0x20/0x30 drivers/most/most_usb.c:932 device_release+0x8c/0x1ac drivers/base/core.c:-1 kobject_cleanup lib/kobject.c:681 [inline] kobject_release lib/kobject.c:712 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x2b0/0x438 lib/kobject.c:729 put_device drivers/base/core.c:3805 [inline] device_unregister+0x3c/0xcc drivers/base/core.c:3929 most_deregister_interface+0x3e0/0x42c drivers/most/core.c:1402 hdm_disconnect+0xdc/0x18c drivers/most/most_usb.c:1123 usb_unbind_interface+0x1b8/0x750 drivers/usb/core/driver.c:458 device_remove drivers/base/dd.c:550 [inline] __device_release_driver drivers/base/dd.c:1260 [inline] device_release_driver_internal+0x424/0x6d0 drivers/base/dd.c:1286 device_release_driver+0x28/0x38 drivers/base/dd.c:1309 bus_remove_device+0x294/0x388 drivers/base/bus.c:531 device_del+0x568/0x96c drivers/base/core.c:3885 usb_disable_device+0x33c/0x780 drivers/usb/core/message.c:1414 usb_disconnect+0x284/0x790 drivers/usb/core/hub.c:2314 hub_port_connect drivers/usb/core/hub.c:5361 [inline] hub_port_connect_change drivers/usb/core/hub.c:5657 [inline] port_event drivers/usb/core/hub.c:5817 [inline] hub_event+0x1644/0x3e2c drivers/usb/core/hub.c:5899 process_one_work+0x7f4/0x13a8 kernel/workqueue.c:2292 process_scheduled_works kernel/workqueue.c:2355 [inline] worker_thread+0xb30/0xfbc kernel/workqueue.c:2441 kthread+0x250/0x2d8 kernel/kthread.c:376 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:849 Last potentially related work creation: kasan_save_stack+0x40/0x70 mm/kasan/common.c:45 __kasan_record_aux_stack+0xc0/0xdc mm/kasan/generic.c:486 kasan_record_aux_stack_noalloc+0x14/0x20 mm/kasan/generic.c:496 call_rcu+0x100/0x954 kernel/rcu/tree.c:2849 fat_put_super+0x98/0xac fs/fat/inode.c:742 generic_shutdown_super+0x130/0x324 fs/super.c:501 kill_block_super+0x70/0xdc fs/super.c:1470 deactivate_locked_super+0xac/0x124 fs/super.c:332 deactivate_super+0xe8/0x108 fs/super.c:363 cleanup_mnt+0x37c/0x404 fs/namespace.c:1182 __cleanup_mnt+0x20/0x30 fs/namespace.c:1189 task_work_run+0x1ec/0x270 kernel/task_work.c:203 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] do_notify_resume+0x1f70/0x2b0c arch/arm64/kernel/signal.c:1137 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline] el0_svc+0x98/0x138 arch/arm64/kernel/entry-common.c:638 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 The buggy address belongs to the object at ffff0000c35dc000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 6320 bytes inside of 8192-byte region [ffff0000c35dc000, ffff0000c35de000) The buggy address belongs to the physical page: page:000000009831d167 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1035d8 head:000000009831d167 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff) raw: 05ffc00000010200 0000000000000000 dead000000000001 ffff0000c0002c00 raw: 0000000000000000 0000000080020002 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000c35dd780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000c35dd800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff0000c35dd880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000c35dd900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000c35dd980: 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: 4438 at lib/refcount.c:28 refcount_warn_saturate+0x154/0x1f8 lib/refcount.c:28 Modules linked in: CPU: 1 PID: 4438 Comm: kworker/1:9 Tainted: G B 6.1.147-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/18/2025 Workqueue: usb_hub_wq hub_event pstate: 62400005 (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 : ffff800021a57400 x29: ffff800021a57400 x28: ffff80001745dda0 x27: 1fffe000186bb800 x26: 1fffe000186bb807 x25: dfff800000000000 x24: ffff0000f4b77030 x23: 1fffe000186bb8a2 x22: ffff0000c35dc03c x21: 0000000000000000 x20: ffff0000c35dc038 x19: ffff800017a78000 x18: ffff800011aabce0 x17: 1fffe00033eddf7e x16: ffff800008042c60 x15: 0000000040000000 x14: 0000000000000002 x13: 0000000000ff0100 x12: 0000000000ff0100 x11: ff00800008047eec x10: 0000000040000002 x9 : a0e9d121d3397700 x8 : a0e9d121d3397700 x7 : 0000000000000004 x6 : ffff800008251ec8 x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000 x2 : ffff800021a56fa0 x1 : 0000000000000000 x0 : ffff800008251f5c Call trace: refcount_warn_saturate+0x154/0x1f8 lib/refcount.c:28 __refcount_sub_and_test include/linux/refcount.h:283 [inline] __refcount_dec_and_test include/linux/refcount.h:315 [inline] refcount_dec_and_test include/linux/refcount.h:333 [inline] kref_put include/linux/kref.h:64 [inline] kobject_put+0x194/0x438 lib/kobject.c:729 put_device+0x28/0x40 drivers/base/core.c:3805 hdm_disconnect+0x174/0x18c drivers/most/most_usb.c:1130 usb_unbind_interface+0x1b8/0x750 drivers/usb/core/driver.c:458 device_remove drivers/base/dd.c:550 [inline] __device_release_driver drivers/base/dd.c:1260 [inline] device_release_driver_internal+0x424/0x6d0 drivers/base/dd.c:1286 device_release_driver+0x28/0x38 drivers/base/dd.c:1309 bus_remove_device+0x294/0x388 drivers/base/bus.c:531 device_del+0x568/0x96c drivers/base/core.c:3885 usb_disable_device+0x33c/0x780 drivers/usb/core/message.c:1414 usb_disconnect+0x284/0x790 drivers/usb/core/hub.c:2314 hub_port_connect drivers/usb/core/hub.c:5361 [inline] hub_port_connect_change drivers/usb/core/hub.c:5657 [inline] port_event drivers/usb/core/hub.c:5817 [inline] hub_event+0x1644/0x3e2c drivers/usb/core/hub.c:5899 process_one_work+0x7f4/0x13a8 kernel/workqueue.c:2292 process_scheduled_works kernel/workqueue.c:2355 [inline] worker_thread+0xb30/0xfbc kernel/workqueue.c:2441 kthread+0x250/0x2d8 kernel/kthread.c:376 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:849 irq event stamp: 46629 hardirqs last enabled at (46629): [] raw_spin_rq_unlock_irq kernel/sched/sched.h:1367 [inline] hardirqs last enabled at (46629): [] finish_lock_switch+0xb0/0x1c4 kernel/sched/core.c:5003 hardirqs last disabled at (46628): [] __schedule+0x298/0x1b18 kernel/sched/core.c:6459 softirqs last enabled at (45920): [] softirq_handle_end kernel/softirq.c:439 [inline] softirqs last enabled at (45920): [] handle_softirqs+0xaf8/0xc6c kernel/softirq.c:624 softirqs last disabled at (45905): [] __do_softirq+0x14/0x20 kernel/softirq.c:630 ---[ end trace 0000000000000000 ]---