================================================================== BUG: KASAN: slab-use-after-free in force_devcd_write+0x312/0x340 drivers/bluetooth/hci_vhci.c:327 Read of size 8 at addr ffff88807615f000 by task syz.0.616/7968 CPU: 0 UID: 0 PID: 7968 Comm: syz.0.616 Not tainted 6.15.0-syzkaller-g7d4e49a77d99 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 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:408 [inline] print_report+0xcd/0x680 mm/kasan/report.c:521 kasan_report+0xe0/0x110 mm/kasan/report.c:634 force_devcd_write+0x312/0x340 drivers/bluetooth/hci_vhci.c:327 full_proxy_write+0x13c/0x200 fs/debugfs/file.c:398 vfs_write+0x2a0/0x1150 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: 0033:0x7faf4c98d169 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:00007faf4d7f4038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007faf4cba5fa0 RCX: 00007faf4c98d169 RDX: 000000000000000e RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00007faf4ca0e2a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007faf4cba5fa0 R15: 00007fff46d1adb8 Allocated by task 6446: 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:377 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394 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+0x35d/0x420 drivers/char/misc.c:179 chrdev_open+0x234/0x6a0 fs/char_dev.c:414 do_dentry_open+0x741/0x1c10 fs/open.c:964 vfs_open+0x82/0x3f0 fs/open.c:1094 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:1437 do_sys_open fs/open.c:1452 [inline] __do_sys_openat fs/open.c:1468 [inline] __se_sys_openat fs/open.c:1463 [inline] __x64_sys_openat+0x174/0x210 fs/open.c:1463 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 6446: 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:247 [inline] __kasan_slab_free+0x51/0x70 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+0x2b4/0x4d0 mm/slub.c:4841 vhci_release+0xbb/0xf0 drivers/bluetooth/hci_vhci.c:671 __fput+0x3ff/0xb70 fs/file_table.c:465 task_work_run+0x150/0x240 kernel/task_work.c:227 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x864/0x2bd0 kernel/exit.c:955 do_group_exit+0xd3/0x2a0 kernel/exit.c:1104 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:111 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:449 [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 ffff88807615f000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 0 bytes inside of freed 1024-byte region [ffff88807615f000, ffff88807615f400) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x76158 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 ffff88801b441dc0 0000000000000000 dead000000000001 raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88801b441dc0 0000000000000000 dead000000000001 head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000 head: 00fff00000000003 ffffea0001d85601 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 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 3546, tgid 3546 (kworker/u8:9), ts 134307033459, free_ts 126677307077 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704 prep_new_page mm/page_alloc.c:1712 [inline] get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419 alloc_slab_page mm/slub.c:2450 [inline] allocate_slab mm/slub.c:2618 [inline] new_slab+0x23b/0x330 mm/slub.c:2672 ___slab_alloc+0xd9c/0x1940 mm/slub.c:3858 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3948 __slab_alloc_node mm/slub.c:4023 [inline] slab_alloc_node mm/slub.c:4184 [inline] __do_kmalloc_node mm/slub.c:4326 [inline] __kmalloc_noprof+0x2f2/0x510 mm/slub.c:4339 kmalloc_noprof include/linux/slab.h:909 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] neigh_alloc net/core/neighbour.c:473 [inline] ___neigh_create+0x14e6/0x28c0 net/core/neighbour.c:607 ip6_finish_output2+0x1299/0x2020 net/ipv6/ip6_output.c:132 __ip6_finish_output net/ipv6/ip6_output.c:215 [inline] ip6_finish_output+0x3f9/0x1360 net/ipv6/ip6_output.c:226 NF_HOOK_COND include/linux/netfilter.h:306 [inline] ip6_output+0x1f9/0x540 net/ipv6/ip6_output.c:247 dst_output include/net/dst.h:459 [inline] NF_HOOK include/linux/netfilter.h:317 [inline] ndisc_send_skb+0xa91/0x1e40 net/ipv6/ndisc.c:513 ndisc_send_rs+0x129/0x670 net/ipv6/ndisc.c:723 addrconf_dad_completed+0x49d/0x10d0 net/ipv6/addrconf.c:4364 addrconf_dad_work+0x84d/0x14e0 net/ipv6/addrconf.c:4272 page last free pid 6282 tgid 6282 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1248 [inline] __free_frozen_pages+0x7fe/0x1180 mm/page_alloc.c:2706 __folio_put+0x329/0x450 mm/swap.c:112 folio_put include/linux/mm.h:1356 [inline] put_page include/linux/mm.h:1425 [inline] put_netmem net/core/skbuff.c:7375 [inline] skb_page_unref include/linux/skbuff_ref.h:43 [inline] __skb_frag_unref include/linux/skbuff_ref.h:56 [inline] skb_release_data+0x7fb/0x9c0 net/core/skbuff.c:1081 skb_release_all net/core/skbuff.c:1152 [inline] __kfree_skb+0x4f/0x70 net/core/skbuff.c:1166 tcp_wmem_free_skb include/net/tcp.h:309 [inline] tcp_rtx_queue_unlink_and_free include/net/tcp.h:2164 [inline] tcp_clean_rtx_queue net/ipv4/tcp_input.c:3441 [inline] tcp_ack+0x19b2/0x5c90 net/ipv4/tcp_input.c:4049 tcp_rcv_established+0x53d/0x22e0 net/ipv4/tcp_input.c:6297 tcp_v4_do_rcv+0x5ca/0xa90 net/ipv4/tcp_ipv4.c:1925 sk_backlog_rcv include/net/sock.h:1148 [inline] __release_sock+0x31b/0x400 net/core/sock.c:3213 __sk_flush_backlog+0x27/0xc0 net/core/sock.c:3233 sk_flush_backlog include/net/sock.h:1211 [inline] tcp_sendmsg_locked+0x399a/0x4300 net/ipv4/tcp.c:1196 tcp_sendmsg+0x2e/0x50 net/ipv4/tcp.c:1396 inet_sendmsg+0xb9/0x140 net/ipv4/af_inet.c:851 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg net/socket.c:727 [inline] sock_write_iter+0x4aa/0x5b0 net/socket.c:1131 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x6c7/0x1150 fs/read_write.c:686 ksys_write+0x1f8/0x250 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 Memory state around the buggy address: ffff88807615ef00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88807615ef80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88807615f000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88807615f080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88807615f100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================