syzbot

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BUG: KASAN: slab-use-after-free in l2cap_sock_ready_cb+0xd5/0x140 net/bluetooth/l2cap_sock.c:1684
Read of size 8 at addr ffff88807f4bb188 by task kworker/u9:4/5840

CPU: 0 UID: 0 PID: 5840 Comm: kworker/u9:4 Not tainted 6.16.0-rc3-syzkaller-00042-g78f4e737a53e #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: hci0 hci_rx_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xd2/0x2b0 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 l2cap_sock_ready_cb+0xd5/0x140 net/bluetooth/l2cap_sock.c:1684
 l2cap_chan_ready net/bluetooth/l2cap_core.c:1263 [inline]
 l2cap_le_start+0xb0a/0x13b0 net/bluetooth/l2cap_core.c:1375
 l2cap_conn_ready net/bluetooth/l2cap_core.c:1628 [inline]
 l2cap_connect_cfm+0x6be/0x1040 net/bluetooth/l2cap_core.c:7281
 hci_connect_cfm+0x95/0x140 include/net/bluetooth/hci_core.h:2054
 le_conn_complete_evt+0xcd3/0x1220 net/bluetooth/hci_event.c:5791
 hci_le_conn_complete_evt+0x187/0x450 net/bluetooth/hci_event.c:5817
 hci_event_func net/bluetooth/hci_event.c:7508 [inline]
 hci_event_packet+0x78c/0x1200 net/bluetooth/hci_event.c:7565
 hci_rx_work+0x46a/0xe80 net/bluetooth/hci_core.c:4044
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 7879:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4328 [inline]
 __kmalloc_noprof+0x27a/0x4f0 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 sk_prot_alloc+0xe7/0x220 net/core/sock.c:2247
 sk_alloc+0x3a/0x370 net/core/sock.c:2303
 bt_sock_alloc+0x3b/0x310 net/bluetooth/af_bluetooth.c:151
 l2cap_sock_alloc net/bluetooth/l2cap_sock.c:1891 [inline]
 l2cap_sock_create+0x147/0x300 net/bluetooth/l2cap_sock.c:1933
 bt_sock_create+0x160/0x240 net/bluetooth/af_bluetooth.c:135
 __sock_create+0x4b0/0x9f0 net/socket.c:1541
 sock_create net/socket.c:1599 [inline]
 __sys_socket_create net/socket.c:1636 [inline]
 __sys_socket+0xd7/0x1b0 net/socket.c:1683
 __do_sys_socket net/socket.c:1697 [inline]
 __se_sys_socket net/socket.c:1695 [inline]
 __x64_sys_socket+0x7a/0x90 net/socket.c:1695
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 7878:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x62/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2381 [inline]
 slab_free mm/slub.c:4643 [inline]
 kfree+0x18e/0x440 mm/slub.c:4842
 sk_prot_free net/core/sock.c:2286 [inline]
 __sk_destruct+0x4e1/0x660 net/core/sock.c:2381
 l2cap_sock_release+0x158/0x1d0 net/bluetooth/l2cap_sock.c:1435
 __sock_release net/socket.c:647 [inline]
 sock_close+0xc0/0x240 net/socket.c:1391
 __fput+0x449/0xa70 fs/file_table.c:465
 task_work_run+0x1d1/0x260 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:114
 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+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88807f4bb000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 392 bytes inside of
 freed 2048-byte region [ffff88807f4bb000, ffff88807f4bb800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7f4b8
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801a842000 ffffea0000cb8800 dead000000000002
raw: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801a842000 ffffea0000cb8800 dead000000000002
head: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea0001fd2e01 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 5832, tgid 5832 (syz-executor), ts 86812415583, free_ts 86801666737
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 alloc_slab_page mm/slub.c:2451 [inline]
 allocate_slab+0x8a/0x3b0 mm/slub.c:2619
 new_slab mm/slub.c:2673 [inline]
 ___slab_alloc+0xbfc/0x1480 mm/slub.c:3859
 __slab_alloc mm/slub.c:3949 [inline]
 __slab_alloc_node mm/slub.c:4024 [inline]
 slab_alloc_node mm/slub.c:4185 [inline]
 __kmalloc_cache_noprof+0x296/0x3d0 mm/slub.c:4354
 kmalloc_noprof include/linux/slab.h:905 [inline]
 rtnl_newlink+0xed/0x1c70 net/core/rtnetlink.c:3955
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x219/0x270 net/socket.c:727
 __sys_sendto+0x3bd/0x520 net/socket.c:2180
 __do_sys_sendto net/socket.c:2187 [inline]
 __se_sys_sendto net/socket.c:2183 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2183
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
page last free pid 5830 tgid 5830 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_frozen_pages+0xc71/0xe70 mm/page_alloc.c:2706
 __slab_free+0x326/0x400 mm/slub.c:4554
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4148 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 __kmalloc_cache_noprof+0x1be/0x3d0 mm/slub.c:4354
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 kset_create lib/kobject.c:965 [inline]
 kset_create_and_add+0x5a/0x170 lib/kobject.c:1008
 register_queue_kobjects net/core/net-sysfs.c:2085 [inline]
 netdev_register_kobject+0x180/0x2f0 net/core/net-sysfs.c:2340
 register_netdevice+0x126c/0x1ae0 net/core/dev.c:11105
 veth_newlink+0x5cc/0xa50 drivers/net/veth.c:1884
 rtnl_newlink_create+0x30d/0xb00 net/core/rtnetlink.c:3823
 __rtnl_newlink net/core/rtnetlink.c:3940 [inline]
 rtnl_newlink+0x16d6/0x1c70 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883

Memory state around the buggy address:
 ffff88807f4bb080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807f4bb100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807f4bb180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88807f4bb200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807f4bb280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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