KASAN: use-after-free Read in bt_accept_unlink

Status: auto-obsoleted due to no activity on 2026/05/11 03:38
Reported-by: syzbot+d17af6e73fda7d970e32@syzkaller.appspotmail.com
First crash: 199d, last: 199d
▶ ▼ Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 KASAN: use-after-free Read in bt_accept_unlink 19 1 433d 433d 0/3 auto-obsoleted due to no activity on 2025/09/18 23:51
linux-6.1 KASAN: slab-out-of-bounds Read in bt_accept_unlink 19 12 8h26m 233d 0/3 upstream: reported on 2025/12/27 18:50
upstream KASAN: slab-use-after-free Read in bt_accept_unlink bluetooth 19 syz 240 1d03h 666d 0/29 upstream: reported syz repro on 2024/10/21 08:47
linux-5.15 KASAN: use-after-free Read in bt_accept_unlink (2) 19 1 79d 79d 0/3 upstream: reported on 2026/05/31 07:00
linux-6.6 KASAN: slab-use-after-free Read in bt_accept_unlink (2) 19 1 42d 42d 0/2 upstream: reported on 2026/07/06 20:50
linux-5.15 BUG: corrupted list in bt_accept_unlink 17 3 455d 496d 0/3 auto-obsoleted due to no activity on 2025/08/27 17:34
linux-6.6 KASAN: slab-out-of-bounds Read in bt_accept_unlink 17 1 427d 427d 0/2 auto-obsoleted due to no activity on 2025/09/25 00:09
upstream general protection fault in bt_accept_unlink (2) bluetooth 2 1 1994d 1990d 0/29 auto-closed as invalid on 2021/07/01 06:33
linux-6.6 KASAN: slab-use-after-free Read in bt_accept_unlink 19 1 319d 319d 0/2 auto-obsoleted due to no activity on 2026/01/11 02:55
linux-5.15 KASAN: slab-out-of-bounds Read in bt_accept_unlink 17 1 315d 315d 0/3 auto-obsoleted due to no activity on 2026/01/15 10:51

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in __list_del_entry_valid+0x80/0x120 lib/list_debug.c:59
Read of size 8 at addr ffff88802612e520 by task syz-executor/4187

CPU: 1 PID: 4187 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 __list_del_entry_valid+0x80/0x120 lib/list_debug.c:59
 __list_del_entry include/linux/list.h:132 [inline]
 list_del_init include/linux/list.h:204 [inline]
 bt_accept_unlink+0x35/0x230 net/bluetooth/af_bluetooth.c:209
 l2cap_sock_teardown_cb+0x1af/0x380 net/bluetooth/l2cap_sock.c:1591
 l2cap_chan_del+0xab/0x620 net/bluetooth/l2cap_core.c:656
 l2cap_conn_del+0x3c1/0x6a0 net/bluetooth/l2cap_core.c:1931
 hci_disconn_cfm include/net/bluetooth/hci_core.h:1520 [inline]
 hci_conn_hash_flush+0x107/0x220 net/bluetooth/hci_conn.c:1622
 hci_dev_do_close+0x991/0x1030 net/bluetooth/hci_core.c:1795
 hci_unregister_dev+0x2d7/0x580 net/bluetooth/hci_core.c:4040
 vhci_release+0x73/0xc0 drivers/bluetooth/hci_vhci.c:345
 __fput+0x234/0x930 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0x626/0x20c0 kernel/exit.c:883
 do_group_exit+0x12e/0x300 kernel/exit.c:997
 __do_sys_exit_group kernel/exit.c:1008 [inline]
 __se_sys_exit_group kernel/exit.c:1006 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1006
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fc9957d6eb9
Code: Unable to access opcode bytes at RIP 0x7fc9957d6e8f.
RSP: 002b:00007ffd622d0978 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007fc9958407c0 RCX: 00007fc9957d6eb9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000016 R08: 0000000000000000 R09: 00007fc99584071f
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd622d1c30
R13: 00007fc99584071f R14: 000055557f26f4e8 R15: 00007ffd622d3df0
 </TASK>

Allocated by task 6172:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc+0xb5/0xf0 mm/kasan/common.c:522
 kmalloc_reserve net/core/skbuff.c:356 [inline]
 pskb_expand_head+0x127/0x10f0 net/core/skbuff.c:1709
 netlink_trim+0x180/0x220 net/netlink/af_netlink.c:1299
 netlink_broadcast_filtered+0x7c/0x1170 net/netlink/af_netlink.c:1511
 netlink_broadcast net/netlink/af_netlink.c:1556 [inline]
 nlmsg_multicast include/net/netlink.h:1033 [inline]
 nlmsg_notify+0xec/0x1a0 net/netlink/af_netlink.c:2550
 rtnl_notify net/core/rtnetlink.c:761 [inline]
 rtmsg_ifinfo_send net/core/rtnetlink.c:3910 [inline]
 rtmsg_ifinfo_event net/core/rtnetlink.c:3925 [inline]
 rtnetlink_event+0x13a/0x1a0 net/core/rtnetlink.c:5735
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
 call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
 call_netdevice_notifiers net/core/dev.c:2075 [inline]
 dev_change_tx_queue_len+0x12a/0x280 net/core/dev.c:9038
 do_setlink+0x1026/0x3d60 net/core/rtnetlink.c:2804
 rtnl_group_changelink net/core/rtnetlink.c:3298 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3462 [inline]
 rtnl_newlink+0xf8d/0x1a50 net/core/rtnetlink.c:3574
 rtnetlink_rcv_msg+0x844/0xf30 net/core/rtnetlink.c:5684
 netlink_rcv_skb+0x1f5/0x440 net/netlink/af_netlink.c:2507
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x774/0x920 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:706 [inline]
 __sock_sendmsg net/socket.c:718 [inline]
 ____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2445
 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2499
 __sys_sendmsg net/socket.c:2528 [inline]
 __do_sys_sendmsg net/socket.c:2537 [inline]
 __se_sys_sendmsg+0x1af/0x290 net/socket.c:2535
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff88802612e000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1312 bytes inside of
 2048-byte region [ffff88802612e000, ffff88802612e800)
The buggy address belongs to the page:
page:ffffea0000984a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88802612d000 pfn:0x26128
head:ffffea0000984a00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffffea0001e2ba08 ffffea0001210608 ffff888016c42000
raw: ffff88802612d000 0000000000080005 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 5940, ts 130324138133, free_ts 130322173869
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x1bbd/0x1ca0 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5487
 alloc_slab_page mm/slub.c:1780 [inline]
 allocate_slab mm/slub.c:1917 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1980
 ___slab_alloc+0x80a/0xdd0 mm/slub.c:3013
 __slab_alloc mm/slub.c:3100 [inline]
 slab_alloc_node mm/slub.c:3191 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 __kmalloc_track_caller+0x1cb/0x330 mm/slub.c:4930
 kmemdup+0x22/0x50 mm/util.c:128
 neigh_sysctl_register+0xaa/0xa90 net/core/neighbour.c:3652
 devinet_sysctl_register+0xa8/0x1f0 net/ipv4/devinet.c:2640
 inetdev_init+0x28c/0x4d0 net/ipv4/devinet.c:277
 inetdev_event+0x26f/0x1370 net/ipv4/devinet.c:1543
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
 call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
 call_netdevice_notifiers net/core/dev.c:2075 [inline]
 register_netdevice+0x129d/0x16f0 net/core/dev.c:10428
 cfg80211_register_netdevice+0x155/0x2f0 net/wireless/core.c:1356
 ieee80211_if_add+0x1022/0x1dc0 net/mac80211/iface.c:2078
 ieee80211_register_hw+0x2bde/0x3af0 net/mac80211/main.c:1323
 mac80211_hwsim_new_radio+0x20d3/0x4080 drivers/net/wireless/mac80211_hwsim.c:3374
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x8f/0x2a0 mm/page_alloc.c:3396
 free_slab mm/slub.c:2020 [inline]
 discard_slab mm/slub.c:2026 [inline]
 __unfreeze_partials+0x1a5/0x200 mm/slub.c:2512
 put_cpu_partial+0x12d/0x190 mm/slub.c:2592
 qlist_free_all+0x35/0x90 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x150/0x160 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xd0 mm/kasan/common.c:444
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x100/0x290 mm/slub.c:3238
 kmem_cache_zalloc include/linux/slab.h:728 [inline]
 __kernfs_new_node+0xe3/0x6c0 fs/kernfs/dir.c:593
 kernfs_new_node+0x148/0x250 fs/kernfs/dir.c:669
 __kernfs_create_file+0x47/0x2e0 fs/kernfs/file.c:985
 sysfs_add_file_mode_ns+0x2d4/0x3a0 fs/sysfs/file.c:317
 create_files fs/sysfs/group.c:64 [inline]
 internal_create_group+0x495/0xd00 fs/sysfs/group.c:149
 netdev_queue_add_kobject net/core/net-sysfs.c:1672 [inline]
 netdev_queue_update_kobjects+0x1bc/0x3e0 net/core/net-sysfs.c:1711
 register_queue_kobjects net/core/net-sysfs.c:1772 [inline]
 netdev_register_kobject+0x273/0x320 net/core/net-sysfs.c:2018

Memory state around the buggy address:
 ffff88802612e400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802612e480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802612e500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff88802612e580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802612e600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/31 03:37 linux-5.15.y 9eec9a14ee10 c75a2f6e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in bt_accept_unlink
* Struck through repros no longer work on HEAD.