================================================================== BUG: KASAN: slab-use-after-free in force_devcd_write+0x312/0x340 drivers/bluetooth/hci_vhci.c:327 Read of size 8 at addr ffff88807cd15000 by task syz.0.4864/3833 CPU: 0 UID: 0 PID: 3833 Comm: syz.0.4864 Not tainted 6.16.0-syzkaller-12063-g37816488247d #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xcd/0x630 mm/kasan/report.c:482 kasan_report+0xe0/0x110 mm/kasan/report.c:595 force_devcd_write+0x312/0x340 drivers/bluetooth/hci_vhci.c:327 full_proxy_write+0x12e/0x1a0 fs/debugfs/file.c:388 vfs_write+0x29d/0x1150 fs/read_write.c:684 ksys_write+0x12a/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f014958ebe9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f01477b4038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f01497b6180 RCX: 00007f014958ebe9 RDX: 000000000000000e RSI: 0000000000000000 RDI: 0000000000000007 RBP: 00007f0149611e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f01497b6218 R14: 00007f01497b6180 R15: 00007fff61251cb8 Allocated by task 22242: kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:388 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:405 kmalloc_noprof include/linux/slab.h:905 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] vhci_open+0x4c/0x430 drivers/bluetooth/hci_vhci.c:635 misc_open+0x35a/0x420 drivers/char/misc.c:161 chrdev_open+0x231/0x6a0 fs/char_dev.c:414 do_dentry_open+0x97f/0x1530 fs/open.c:965 vfs_open+0x82/0x3f0 fs/open.c:1095 do_open fs/namei.c:3887 [inline] path_openat+0x1de4/0x2cb0 fs/namei.c:4046 do_filp_open+0x20b/0x470 fs/namei.c:4073 do_sys_openat2+0x11b/0x1d0 fs/open.c:1435 do_sys_open fs/open.c:1450 [inline] __do_sys_openat fs/open.c:1466 [inline] __se_sys_openat fs/open.c:1461 [inline] __x64_sys_openat+0x174/0x210 fs/open.c:1461 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 22242: kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:243 [inline] __kasan_slab_free+0x60/0x70 mm/kasan/common.c:275 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2417 [inline] slab_free mm/slub.c:4680 [inline] kfree+0x2b4/0x4d0 mm/slub.c:4879 vhci_release+0xbb/0xf0 drivers/bluetooth/hci_vhci.c:671 __fput+0x3ff/0xb70 fs/file_table.c:468 task_work_run+0x150/0x240 kernel/task_work.c:227 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x86f/0x2bf0 kernel/exit.c:961 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102 get_signal+0x2673/0x26d0 kernel/signal.c:3034 arch_do_signal_or_restart+0x8f/0x790 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop+0x84/0x110 kernel/entry/common.c:40 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] do_syscall_64+0x3f6/0x490 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88807cd15000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 0 bytes inside of freed 1024-byte region [ffff88807cd15000, ffff88807cd15400) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7cd10 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88801b841dc0 0000000000000000 dead000000000001 raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88801b841dc0 0000000000000000 dead000000000001 head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000 head: 00fff00000000003 ffffea0001f34401 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5970, tgid 5970 (syz.3.4), ts 119100576662, free_ts 118740447398 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851 prep_new_page mm/page_alloc.c:1859 [inline] get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416 alloc_slab_page mm/slub.c:2487 [inline] allocate_slab mm/slub.c:2655 [inline] new_slab+0x247/0x330 mm/slub.c:2709 ___slab_alloc+0xcf2/0x1740 mm/slub.c:3891 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3981 __slab_alloc_node mm/slub.c:4056 [inline] slab_alloc_node mm/slub.c:4217 [inline] __kmalloc_cache_noprof+0xfb/0x3e0 mm/slub.c:4391 kmalloc_noprof include/linux/slab.h:905 [inline] snd_pcm_hw_param_near.constprop.0+0xbc/0x8e0 sound/core/oss/pcm_oss.c:400 snd_pcm_oss_change_params_locked+0x1398/0x3a30 sound/core/oss/pcm_oss.c:954 snd_pcm_oss_change_params sound/core/oss/pcm_oss.c:1104 [inline] snd_pcm_oss_make_ready+0xe6/0x1b0 sound/core/oss/pcm_oss.c:1163 snd_pcm_oss_sync+0x1de/0x840 sound/core/oss/pcm_oss.c:1729 snd_pcm_oss_release+0x28b/0x310 sound/core/oss/pcm_oss.c:2574 __fput+0x3ff/0xb70 fs/file_table.c:468 task_work_run+0x150/0x240 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xeb/0x110 kernel/entry/common.c:43 page last free pid 5981 tgid 5970 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1395 [inline] __free_frozen_pages+0x7d5/0x10f0 mm/page_alloc.c:2895 discard_slab mm/slub.c:2753 [inline] __put_partials+0x165/0x1c0 mm/slub.c:3218 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x4d/0x120 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:340 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4180 [inline] slab_alloc_node mm/slub.c:4229 [inline] kmem_cache_alloc_node_noprof+0x1d5/0x3b0 mm/slub.c:4281 kmalloc_reserve+0x18b/0x2c0 net/core/skbuff.c:578 __alloc_skb+0x166/0x380 net/core/skbuff.c:669 alloc_skb include/linux/skbuff.h:1336 [inline] alloc_skb_with_frags+0xe0/0x860 net/core/skbuff.c:6665 sock_alloc_send_pskb+0x7fb/0x990 net/core/sock.c:2980 sock_alloc_send_skb include/net/sock.h:1847 [inline] __ip_append_data+0x2149/0x41c0 net/ipv4/ip_output.c:1125 ip_make_skb+0x27f/0x300 net/ipv4/ip_output.c:1572 udp_sendmsg+0x17d7/0x2870 net/ipv4/udp.c:1479 inet_sendmsg+0x105/0x140 net/ipv4/af_inet.c:851 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg net/socket.c:729 [inline] ____sys_sendmsg+0x973/0xc70 net/socket.c:2614 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2668 Memory state around the buggy address: ffff88807cd14f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88807cd14f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88807cd15000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88807cd15080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88807cd15100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================