================================================================== BUG: KASAN: use-after-free in kobject_get+0x113/0x120 lib/kobject.c:663 Read of size 1 at addr ffff88811a62883c by task syz.2.1584/6805 CPU: 1 PID: 6805 Comm: syz.2.1584 Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 Call Trace: __dump_stack+0x21/0x24 lib/dump_stack.c:77 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:435 [inline] kasan_report+0x100/0x140 mm/kasan/report.c:452 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:306 kobject_get+0x113/0x120 lib/kobject.c:663 get_device drivers/base/core.c:3361 [inline] device_add+0x331/0xc00 drivers/base/core.c:3191 device_create_groups_vargs drivers/base/core.c:3960 [inline] device_create+0x26c/0x300 drivers/base/core.c:4002 create_function_device+0x60/0x70 drivers/usb/gadget/configfs.c:31 create_alsa_device drivers/usb/gadget/function/f_midi.c:1262 [inline] f_midi_alloc_inst+0x1a8/0x380 drivers/usb/gadget/function/f_midi.c:1303 try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline] usb_get_function_instance+0xe2/0x2f0 drivers/usb/gadget/functions.c:44 function_make+0x118/0x350 drivers/usb/gadget/configfs.c:636 configfs_mkdir+0x5d2/0xd90 fs/configfs/dir.c:1378 vfs_mkdir+0x42c/0x600 fs/namei.c:3840 do_mkdirat+0x14c/0x340 fs/namei.c:3862 __do_sys_mkdirat fs/namei.c:3873 [inline] __se_sys_mkdirat fs/namei.c:3871 [inline] __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3871 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7fc1bdcf8559 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc1bc750028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 00007fc1bdf7efa0 RCX: 00007fc1bdcf8559 RDX: 00000000000001ff RSI: 0000200000002200 RDI: ffffffffffffff9c RBP: 00007fc1bdd8fb20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc1bdf7f038 R14: 00007fc1bdf7efa0 R15: 00007ffd053d3608 Allocated by task 4580: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:430 [inline] __kasan_slab_alloc+0xb7/0xe0 mm/kasan/common.c:463 kasan_slab_alloc include/linux/kasan.h:244 [inline] slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580 slab_alloc_node mm/slub.c:2952 [inline] slab_alloc mm/slub.c:2960 [inline] kmem_cache_alloc+0x15a/0x2d0 mm/slub.c:2965 getname_flags+0xba/0x510 fs/namei.c:141 getname fs/namei.c:212 [inline] do_symlinkat+0x48/0x3d0 fs/namei.c:4165 __do_sys_symlink fs/namei.c:4195 [inline] __se_sys_symlink fs/namei.c:4193 [inline] __x64_sys_symlink+0x60/0x70 fs/namei.c:4193 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb Freed by task 4580: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4a/0x70 mm/kasan/common.c:45 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370 kasan_slab_free include/linux/kasan.h:220 [inline] slab_free_hook mm/slub.c:1600 [inline] slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626 slab_free mm/slub.c:3208 [inline] kmem_cache_free+0x100/0x2d0 mm/slub.c:3224 putname fs/namei.c:262 [inline] do_symlinkat+0x35b/0x3d0 fs/namei.c:4183 __do_sys_symlink fs/namei.c:4195 [inline] __se_sys_symlink fs/namei.c:4193 [inline] __x64_sys_symlink+0x60/0x70 fs/namei.c:4193 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb The buggy address belongs to the object at ffff88811a628000 which belongs to the cache names_cache of size 4096 The buggy address is located 2108 bytes inside of 4096-byte region [ffff88811a628000, ffff88811a629000) The buggy address belongs to the page: page:ffffea0004698a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11a628 head:ffffea0004698a00 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head) raw: 4000000000010200 dead000000000100 dead000000000122 ffff88810018b500 raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 2830, ts 248205197471, free_ts 248144676143 set_page_owner include/linux/page_owner.h:35 [inline] post_alloc_hook mm/page_alloc.c:2456 [inline] prep_new_page+0x176/0x190 mm/page_alloc.c:2462 get_page_from_freelist+0x225f/0x23f0 mm/page_alloc.c:4254 __alloc_pages_nodemask+0x29a/0x640 mm/page_alloc.c:5384 alloc_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1813 [inline] new_slab+0x84/0x3f0 mm/slub.c:1874 new_slab_objects mm/slub.c:2632 [inline] ___slab_alloc+0x2f8/0x4c0 mm/slub.c:2796 __slab_alloc+0x63/0xa0 mm/slub.c:2836 slab_alloc_node mm/slub.c:2918 [inline] slab_alloc mm/slub.c:2960 [inline] kmem_cache_alloc+0x1a4/0x2d0 mm/slub.c:2965 getname_flags+0xba/0x510 fs/namei.c:141 user_path_at_empty+0x2f/0x50 fs/namei.c:2790 user_path_at include/linux/namei.h:60 [inline] vfs_statx+0x10a/0x530 fs/stat.c:193 vfs_fstatat fs/stat.c:215 [inline] __do_sys_newfstatat fs/stat.c:383 [inline] __se_sys_newfstatat+0x10e/0x3d0 fs/stat.c:377 __x64_sys_newfstatat+0x9b/0xb0 fs/stat.c:377 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb page last free stack trace: reset_page_owner include/linux/page_owner.h:28 [inline] free_pages_prepare mm/page_alloc.c:1349 [inline] __free_pages_ok+0x80b/0x830 mm/page_alloc.c:1629 free_the_page mm/page_alloc.c:5445 [inline] __free_pages+0xd8/0x390 mm/page_alloc.c:5454 __free_slab+0xcf/0x190 mm/slub.c:1899 free_slab mm/slub.c:1914 [inline] discard_slab+0x29/0x40 mm/slub.c:1920 __slab_free+0x313/0x3a0 mm/slub.c:3136 do_slab_free mm/slub.c:3196 [inline] ___cache_free+0x10e/0x130 mm/slub.c:3215 qlink_free+0x50/0x90 mm/kasan/quarantine.c:157 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176 kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283 __kasan_slab_alloc+0x2f/0xe0 mm/kasan/common.c:440 kasan_slab_alloc include/linux/kasan.h:244 [inline] slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580 slab_alloc_node mm/slub.c:2952 [inline] slab_alloc mm/slub.c:2960 [inline] kmem_cache_alloc_trace+0x155/0x2e0 mm/slub.c:2977 kmalloc include/linux/slab.h:555 [inline] copy_mount_options fs/namespace.c:3214 [inline] __do_sys_mount fs/namespace.c:3552 [inline] __se_sys_mount+0x153/0x390 fs/namespace.c:3534 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3534 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb Memory state around the buggy address: ffff88811a628700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88811a628780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88811a628800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88811a628880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88811a628900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== ------------[ cut here ]------------ kobject: '(null)' (ffff88811a628800): is not initialized, yet kobject_get() is being called. WARNING: CPU: 1 PID: 6805 at lib/kobject.c:666 kobject_get+0x7c/0x120 lib/kobject.c:664 Modules linked in: CPU: 1 PID: 6805 Comm: syz.2.1584 Tainted: G B W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 RIP: 0010:kobject_get+0x7c/0x120 lib/kobject.c:664 Code: 0a ff 48 89 d8 48 c1 e8 03 42 80 3c 38 00 74 08 48 89 df e8 16 3b 45 ff 48 8b 33 48 c7 c7 00 a6 41 85 48 89 da e8 a4 30 20 02 <0f> 0b eb 0c e8 1b ad 0a ff eb 4c e8 14 ad 0a ff 4c 8d 73 38 4c 89 RSP: 0018:ffffc900008ff970 EFLAGS: 00010246 RAX: 791c86f4e4230900 RBX: ffff88811a628800 RCX: 0000000000080000 RDX: ffffc90003152000 RSI: 000000000007ffff RDI: 0000000000080000 RBP: ffffc900008ff988 R08: ffff8881f7152fff R09: 1ffff1103ee2a5ff R10: dffffc0000000000 R11: ffffed103ee2a600 R12: 0000000000000000 R13: ffff888146fb1068 R14: 0000000000000000 R15: dffffc0000000000 FS: 00007fc1bc7506c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffcb615cfa8 CR3: 000000012034e000 CR4: 00000000003506a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: get_device drivers/base/core.c:3361 [inline] device_add+0x331/0xc00 drivers/base/core.c:3191 device_create_groups_vargs drivers/base/core.c:3960 [inline] device_create+0x26c/0x300 drivers/base/core.c:4002 create_function_device+0x60/0x70 drivers/usb/gadget/configfs.c:31 create_alsa_device drivers/usb/gadget/function/f_midi.c:1262 [inline] f_midi_alloc_inst+0x1a8/0x380 drivers/usb/gadget/function/f_midi.c:1303 try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline] usb_get_function_instance+0xe2/0x2f0 drivers/usb/gadget/functions.c:44 function_make+0x118/0x350 drivers/usb/gadget/configfs.c:636 configfs_mkdir+0x5d2/0xd90 fs/configfs/dir.c:1378 vfs_mkdir+0x42c/0x600 fs/namei.c:3840 do_mkdirat+0x14c/0x340 fs/namei.c:3862 __do_sys_mkdirat fs/namei.c:3873 [inline] __se_sys_mkdirat fs/namei.c:3871 [inline] __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3871 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7fc1bdcf8559 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc1bc750028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 00007fc1bdf7efa0 RCX: 00007fc1bdcf8559 RDX: 00000000000001ff RSI: 0000200000002200 RDI: ffffffffffffff9c RBP: 00007fc1bdd8fb20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc1bdf7f038 R14: 00007fc1bdf7efa0 R15: 00007ffd053d3608 ---[ end trace bd1131a4d08d9202 ]--- ------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 1 PID: 6805 at lib/refcount.c:25 refcount_warn_saturate+0x104/0x1a0 lib/refcount.c:25 Modules linked in: CPU: 1 PID: 6805 Comm: syz.2.1584 Tainted: G B W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 RIP: 0010:refcount_warn_saturate+0x104/0x1a0 lib/refcount.c:25 Code: 04 01 48 c7 c7 80 53 40 85 e8 78 04 3c 02 0f 0b eb df e8 ef 80 26 ff c6 05 cd 70 82 04 01 48 c7 c7 c0 52 40 85 e8 5c 04 3c 02 <0f> 0b eb c3 e8 d3 80 26 ff c6 05 b2 70 82 04 01 48 c7 c7 20 53 40 RSP: 0018:ffffc900008ff950 EFLAGS: 00010246 RAX: 791c86f4e4230900 RBX: 0000000000000002 RCX: 0000000000080000 RDX: ffffc90003152000 RSI: 000000000007ffff RDI: 0000000000080000 RBP: ffffc900008ff960 R08: ffff8881f7127493 R09: 1ffff1103ee24e92 R10: dffffc0000000000 R11: ffffed103ee24e93 R12: 0000000000000000 R13: ffff888146fb1068 R14: 0000000000000002 R15: 0000000000000000 FS: 00007fc1bc7506c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f15fad3f048 CR3: 000000012034e000 CR4: 00000000003506a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __refcount_add include/linux/refcount.h:-1 [inline] __refcount_inc include/linux/refcount.h:250 [inline] refcount_inc include/linux/refcount.h:267 [inline] kref_get include/linux/kref.h:45 [inline] kobject_get+0xfb/0x120 lib/kobject.c:667 get_device drivers/base/core.c:3361 [inline] device_add+0x331/0xc00 drivers/base/core.c:3191 device_create_groups_vargs drivers/base/core.c:3960 [inline] device_create+0x26c/0x300 drivers/base/core.c:4002 create_function_device+0x60/0x70 drivers/usb/gadget/configfs.c:31 create_alsa_device drivers/usb/gadget/function/f_midi.c:1262 [inline] f_midi_alloc_inst+0x1a8/0x380 drivers/usb/gadget/function/f_midi.c:1303 try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline] usb_get_function_instance+0xe2/0x2f0 drivers/usb/gadget/functions.c:44 function_make+0x118/0x350 drivers/usb/gadget/configfs.c:636 configfs_mkdir+0x5d2/0xd90 fs/configfs/dir.c:1378 vfs_mkdir+0x42c/0x600 fs/namei.c:3840 do_mkdirat+0x14c/0x340 fs/namei.c:3862 __do_sys_mkdirat fs/namei.c:3873 [inline] __se_sys_mkdirat fs/namei.c:3871 [inline] __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3871 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7fc1bdcf8559 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc1bc750028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 00007fc1bdf7efa0 RCX: 00007fc1bdcf8559 RDX: 00000000000001ff RSI: 0000200000002200 RDI: ffffffffffffff9c RBP: 00007fc1bdd8fb20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc1bdf7f038 R14: 00007fc1bdf7efa0 R15: 00007ffd053d3608 ---[ end trace bd1131a4d08d9203 ]--- ------------[ cut here ]------------ kobject: '(null)' (ffff88811a628800): is not initialized, yet kobject_get() is being called. WARNING: CPU: 1 PID: 6805 at lib/kobject.c:666 kobject_get lib/kobject.c:664 [inline] WARNING: CPU: 1 PID: 6805 at lib/kobject.c:666 kobject_add_internal+0x12e/0xde0 lib/kobject.c:248 Modules linked in: CPU: 1 PID: 6805 Comm: syz.2.1584 Tainted: G B W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 RIP: 0010:kobject_get lib/kobject.c:664 [inline] RIP: 0010:kobject_add_internal+0x12e/0xde0 lib/kobject.c:248 Code: b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 4c 89 e7 e8 95 22 45 ff 49 8b 34 24 48 c7 c7 00 a6 41 85 4c 89 e2 e8 22 18 20 02 <0f> 0b e9 04 01 00 00 e8 96 94 0a ff b8 fe ff ff ff e9 b0 09 00 00 RSP: 0018:ffffc900008ff7d8 EFLAGS: 00010246 RAX: 791c86f4e4230900 RBX: ffff8881057b7600 RCX: 0000000000080000 RDX: ffffc90003152000 RSI: 000000000007ffff RDI: 0000000000080000 RBP: ffffc900008ff830 R08: ffffc900008ff167 R09: fffff5200011fe60 R10: dffffc0000000000 R11: fffff5200011fe2d R12: ffff88811a628800 R13: ffff8881057b7618 R14: 0000000000000000 R15: 1ffff11020af6ec0 FS: 00007fc1bc7506c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f15fad3f048 CR3: 000000012034e000 CR4: 00000000003506a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: kobject_add_varg lib/kobject.c:398 [inline] kobject_add+0x165/0x230 lib/kobject.c:450 class_dir_create_and_add drivers/base/core.c:2825 [inline] get_device_parent+0x3a6/0x410 drivers/base/core.c:2880 device_add+0x349/0xc00 drivers/base/core.c:3192 device_create_groups_vargs drivers/base/core.c:3960 [inline] device_create+0x26c/0x300 drivers/base/core.c:4002 create_function_device+0x60/0x70 drivers/usb/gadget/configfs.c:31 create_alsa_device drivers/usb/gadget/function/f_midi.c:1262 [inline] f_midi_alloc_inst+0x1a8/0x380 drivers/usb/gadget/function/f_midi.c:1303 try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline] usb_get_function_instance+0xe2/0x2f0 drivers/usb/gadget/functions.c:44 function_make+0x118/0x350 drivers/usb/gadget/configfs.c:636 configfs_mkdir+0x5d2/0xd90 fs/configfs/dir.c:1378 vfs_mkdir+0x42c/0x600 fs/namei.c:3840 do_mkdirat+0x14c/0x340 fs/namei.c:3862 __do_sys_mkdirat fs/namei.c:3873 [inline] __se_sys_mkdirat fs/namei.c:3871 [inline] __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3871 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7fc1bdcf8559 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc1bc750028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 00007fc1bdf7efa0 RCX: 00007fc1bdcf8559 RDX: 00000000000001ff RSI: 0000200000002200 RDI: ffffffffffffff9c RBP: 00007fc1bdd8fb20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc1bdf7f038 R14: 00007fc1bdf7efa0 R15: 00007ffd053d3608 ---[ end trace bd1131a4d08d9204 ]--- ------------[ cut here ]------------ refcount_t: saturated; leaking memory. WARNING: CPU: 1 PID: 6805 at lib/refcount.c:22 refcount_warn_saturate+0x158/0x1a0 lib/refcount.c:22 Modules linked in: CPU: 1 PID: 6805 Comm: syz.2.1584 Tainted: G B W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 RIP: 0010:refcount_warn_saturate+0x158/0x1a0 lib/refcount.c:22 Code: 04 01 48 c7 c7 40 52 40 85 e8 24 04 3c 02 0f 0b eb 8b e8 9b 80 26 ff c6 05 78 70 82 04 01 48 c7 c7 40 52 40 85 e8 08 04 3c 02 <0f> 0b e9 6c ff ff ff e8 7c 80 26 ff c6 05 5d 70 82 04 01 48 c7 c7 RSP: 0018:ffffc900008ff7b8 EFLAGS: 00010246 RAX: 791c86f4e4230900 RBX: 0000000000000001 RCX: 0000000000080000 RDX: ffffc90003152000 RSI: 000000000007ffff RDI: 0000000000080000 RBP: ffffc900008ff7c8 R08: ffffc900008ff147 R09: fffff5200011fe5c R10: dffffc0000000000 R11: fffff5200011fe29 R12: 00000000c0000000 R13: ffff8881057b7618 R14: 0000000000000001 R15: ffff88811a628838 FS: 00007fc1bc7506c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f15fad3f048 CR3: 000000012034e000 CR4: 00000000003506a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __refcount_add include/linux/refcount.h:-1 [inline] __refcount_inc include/linux/refcount.h:250 [inline] refcount_inc include/linux/refcount.h:267 [inline] kref_get include/linux/kref.h:45 [inline] kobject_get lib/kobject.c:667 [inline] kobject_add_internal+0xc44/0xde0 lib/kobject.c:248 kobject_add_varg lib/kobject.c:398 [inline] kobject_add+0x165/0x230 lib/kobject.c:450 class_dir_create_and_add drivers/base/core.c:2825 [inline] get_device_parent+0x3a6/0x410 drivers/base/core.c:2880 device_add+0x349/0xc00 drivers/base/core.c:3192 device_create_groups_vargs drivers/base/core.c:3960 [inline] device_create+0x26c/0x300 drivers/base/core.c:4002 create_function_device+0x60/0x70 drivers/usb/gadget/configfs.c:31 create_alsa_device drivers/usb/gadget/function/f_midi.c:1262 [inline] f_midi_alloc_inst+0x1a8/0x380 drivers/usb/gadget/function/f_midi.c:1303 try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline] usb_get_function_instance+0xe2/0x2f0 drivers/usb/gadget/functions.c:44 function_make+0x118/0x350 drivers/usb/gadget/configfs.c:636 configfs_mkdir+0x5d2/0xd90 fs/configfs/dir.c:1378 vfs_mkdir+0x42c/0x600 fs/namei.c:3840 do_mkdirat+0x14c/0x340 fs/namei.c:3862 __do_sys_mkdirat fs/namei.c:3873 [inline] __se_sys_mkdirat fs/namei.c:3871 [inline] __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3871 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7fc1bdcf8559 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc1bc750028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 00007fc1bdf7efa0 RCX: 00007fc1bdcf8559 RDX: 00000000000001ff RSI: 0000200000002200 RDI: ffffffffffffff9c RBP: 00007fc1bdd8fb20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc1bdf7f038 R14: 00007fc1bdf7efa0 R15: 00007ffd053d3608 ---[ end trace bd1131a4d08d9205 ]--- ------------[ cut here ]------------ kobject: '(null)' (ffff88811a628800): is not initialized, yet kobject_put() is being called. WARNING: CPU: 1 PID: 6805 at lib/kobject.c:760 kobject_put+0x8a/0x270 lib/kobject.c:758 Modules linked in: CPU: 1 PID: 6805 Comm: syz.2.1584 Tainted: G B W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 RIP: 0010:kobject_put+0x8a/0x270 lib/kobject.c:758 Code: 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 48 89 df e8 e8 39 45 ff 48 8b 33 48 c7 c7 80 a6 41 85 48 89 da e8 76 2f 20 02 <0f> 0b eb 0f e8 ed ab 0a ff e9 7c 01 00 00 e8 e3 ab 0a ff 4c 8d 7b RSP: 0018:ffffc900008ff7a0 EFLAGS: 00010246 RAX: 791c86f4e4230900 RBX: ffff88811a628800 RCX: 0000000000080000 RDX: ffffc90003152000 RSI: 000000000007ffff RDI: 0000000000080000 RBP: ffffc900008ff7c8 R08: ffff8881f7152fff R09: 1ffff1103ee2a5ff R10: dffffc0000000000 R11: ffffed103ee2a600 R12: ffff88811a628800 R13: ffff88811a62883c R14: 1ffff110234c5107 R15: 0000000000000000 FS: 00007fc1bc7506c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f15fad3f048 CR3: 000000012034e000 CR4: 00000000003506a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: kobject_add_internal+0xb52/0xde0 lib/kobject.c:266 kobject_add_varg lib/kobject.c:398 [inline] kobject_add+0x165/0x230 lib/kobject.c:450 class_dir_create_and_add drivers/base/core.c:2825 [inline] get_device_parent+0x3a6/0x410 drivers/base/core.c:2880 device_add+0x349/0xc00 drivers/base/core.c:3192 device_create_groups_vargs drivers/base/core.c:3960 [inline] device_create+0x26c/0x300 drivers/base/core.c:4002 create_function_device+0x60/0x70 drivers/usb/gadget/configfs.c:31 create_alsa_device drivers/usb/gadget/function/f_midi.c:1262 [inline] f_midi_alloc_inst+0x1a8/0x380 drivers/usb/gadget/function/f_midi.c:1303 try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline] usb_get_function_instance+0xe2/0x2f0 drivers/usb/gadget/functions.c:44 function_make+0x118/0x350 drivers/usb/gadget/configfs.c:636 configfs_mkdir+0x5d2/0xd90 fs/configfs/dir.c:1378 vfs_mkdir+0x42c/0x600 fs/namei.c:3840 do_mkdirat+0x14c/0x340 fs/namei.c:3862 __do_sys_mkdirat fs/namei.c:3873 [inline] __se_sys_mkdirat fs/namei.c:3871 [inline] __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3871 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7fc1bdcf8559 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc1bc750028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 00007fc1bdf7efa0 RCX: 00007fc1bdcf8559 RDX: 00000000000001ff RSI: 0000200000002200 RDI: ffffffffffffff9c RBP: 00007fc1bdd8fb20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc1bdf7f038 R14: 00007fc1bdf7efa0 R15: 00007ffd053d3608 ---[ end trace bd1131a4d08d9206 ]--- ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 6805 at lib/refcount.c:28 refcount_warn_saturate+0x120/0x1a0 lib/refcount.c:28 Modules linked in: CPU: 1 PID: 6805 Comm: syz.2.1584 Tainted: G B W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 RIP: 0010:refcount_warn_saturate+0x120/0x1a0 lib/refcount.c:28 Code: 04 01 48 c7 c7 c0 52 40 85 e8 5c 04 3c 02 0f 0b eb c3 e8 d3 80 26 ff c6 05 b2 70 82 04 01 48 c7 c7 20 53 40 85 e8 40 04 3c 02 <0f> 0b eb a7 e8 b7 80 26 ff c6 05 93 70 82 04 01 48 c7 c7 40 52 40 RSP: 0018:ffffc900008ff780 EFLAGS: 00010246 RAX: 791c86f4e4230900 RBX: 0000000000000003 RCX: 0000000000080000 RDX: ffffc90003152000 RSI: 000000000007ffff RDI: 0000000000080000 RBP: ffffc900008ff790 R08: ffff8881f7152fff R09: 1ffff1103ee2a5ff R10: dffffc0000000000 R11: ffffed103ee2a600 R12: 00000000c0000000 R13: ffff88811a62883c R14: 0000000000000003 R15: ffff88811a628838 FS: 00007fc1bc7506c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f15fad3f048 CR3: 000000012034e000 CR4: 00000000003506a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __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+0x231/0x270 lib/kobject.c:761 kobject_add_internal+0xb52/0xde0 lib/kobject.c:266 kobject_add_varg lib/kobject.c:398 [inline] kobject_add+0x165/0x230 lib/kobject.c:450 class_dir_create_and_add drivers/base/core.c:2825 [inline] get_device_parent+0x3a6/0x410 drivers/base/core.c:2880 device_add+0x349/0xc00 drivers/base/core.c:3192 device_create_groups_vargs drivers/base/core.c:3960 [inline] device_create+0x26c/0x300 drivers/base/core.c:4002 create_function_device+0x60/0x70 drivers/usb/gadget/configfs.c:31 create_alsa_device drivers/usb/gadget/function/f_midi.c:1262 [inline] f_midi_alloc_inst+0x1a8/0x380 drivers/usb/gadget/function/f_midi.c:1303 try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline] usb_get_function_instance+0xe2/0x2f0 drivers/usb/gadget/functions.c:44 function_make+0x118/0x350 drivers/usb/gadget/configfs.c:636 configfs_mkdir+0x5d2/0xd90 fs/configfs/dir.c:1378 vfs_mkdir+0x42c/0x600 fs/namei.c:3840 do_mkdirat+0x14c/0x340 fs/namei.c:3862 __do_sys_mkdirat fs/namei.c:3873 [inline] __se_sys_mkdirat fs/namei.c:3871 [inline] __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3871 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7fc1bdcf8559 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc1bc750028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 00007fc1bdf7efa0 RCX: 00007fc1bdcf8559 RDX: 00000000000001ff RSI: 0000200000002200 RDI: ffffffffffffff9c RBP: 00007fc1bdd8fb20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc1bdf7f038 R14: 00007fc1bdf7efa0 R15: 00007ffd053d3608 ---[ end trace bd1131a4d08d9207 ]--- kobject_add_internal failed for android_usb (error: -2 parent: (null)) ------------[ cut here ]------------ kobject: '(null)' (ffff88811a628800): is not initialized, yet kobject_put() is being called. WARNING: CPU: 1 PID: 6805 at lib/kobject.c:760 kobject_put+0x8a/0x270 lib/kobject.c:758 Modules linked in: CPU: 1 PID: 6805 Comm: syz.2.1584 Tainted: G B W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 RIP: 0010:kobject_put+0x8a/0x270 lib/kobject.c:758 Code: 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 48 89 df e8 e8 39 45 ff 48 8b 33 48 c7 c7 80 a6 41 85 48 89 da e8 76 2f 20 02 <0f> 0b eb 0f e8 ed ab 0a ff e9 7c 01 00 00 e8 e3 ab 0a ff 4c 8d 7b RSP: 0018:ffffc900008ff960 EFLAGS: 00010246 RAX: 791c86f4e4230900 RBX: ffff88811a628800 RCX: 0000000000080000 RDX: ffffc90003152000 RSI: 000000000007ffff RDI: 0000000000080000 RBP: ffffc900008ff988 R08: ffff8881f7152fff R09: 1ffff1103ee2a5ff R10: dffffc0000000000 R11: ffffed103ee2a600 R12: fffffffffffffffe R13: ffff88811a62883c R14: 1ffff110234c5107 R15: 0000000000000000 FS: 00007fc1bc7506c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f15fad3f048 CR3: 000000012034e000 CR4: 00000000003506a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: put_device drivers/base/core.c:3373 [inline] device_add+0x36f/0xc00 drivers/base/core.c:3318 device_create_groups_vargs drivers/base/core.c:3960 [inline] device_create+0x26c/0x300 drivers/base/core.c:4002 create_function_device+0x60/0x70 drivers/usb/gadget/configfs.c:31 create_alsa_device drivers/usb/gadget/function/f_midi.c:1262 [inline] f_midi_alloc_inst+0x1a8/0x380 drivers/usb/gadget/function/f_midi.c:1303 try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline] usb_get_function_instance+0xe2/0x2f0 drivers/usb/gadget/functions.c:44 function_make+0x118/0x350 drivers/usb/gadget/configfs.c:636 configfs_mkdir+0x5d2/0xd90 fs/configfs/dir.c:1378 vfs_mkdir+0x42c/0x600 fs/namei.c:3840 do_mkdirat+0x14c/0x340 fs/namei.c:3862 __do_sys_mkdirat fs/namei.c:3873 [inline] __se_sys_mkdirat fs/namei.c:3871 [inline] __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3871 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7fc1bdcf8559 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc1bc750028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 00007fc1bdf7efa0 RCX: 00007fc1bdcf8559 RDX: 00000000000001ff RSI: 0000200000002200 RDI: ffffffffffffff9c RBP: 00007fc1bdd8fb20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc1bdf7f038 R14: 00007fc1bdf7efa0 R15: 00007ffd053d3608 ---[ end trace bd1131a4d08d9208 ]---