syzbot

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BUG: KASAN: use-after-free in hci_uart_write_work+0x4ad/0x7b0 drivers/bluetooth/hci_ldisc.c:165
Read of size 8 at addr ffff8881436e24a8 by task kworker/1:3/344

CPU: 1 PID: 344 Comm: kworker/1:3 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: events hci_uart_write_work
Call Trace:
 <TASK>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0xee/0x150 lib/dump_stack.c:106
 print_address_description+0x71/0x1e0 mm/kasan/report.c:316
 print_report+0x4a/0x60 mm/kasan/report.c:418
 kasan_report+0x122/0x150 mm/kasan/report.c:522
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:351
 hci_uart_write_work+0x4ad/0x7b0 drivers/bluetooth/hci_ldisc.c:165
 process_one_work+0x71f/0xc40 kernel/workqueue.c:2302
 worker_thread+0xa29/0x11f0 kernel/workqueue.c:2449
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Allocated by task 45:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 kasan_save_alloc_info+0x25/0x30 mm/kasan/generic.c:505
 __kasan_slab_alloc+0x72/0x80 mm/kasan/common.c:333
 kasan_slab_alloc include/linux/kasan.h:202 [inline]
 slab_post_alloc_hook+0x4f/0x2d0 mm/slab.h:768
 slab_alloc_node mm/slub.c:3421 [inline]
 kmem_cache_alloc_node+0x181/0x340 mm/slub.c:3468
 __alloc_skb+0xea/0x4b0 net/core/skbuff.c:508
 alloc_skb include/linux/skbuff.h:1290 [inline]
 bt_skb_alloc include/net/bluetooth/bluetooth.h:473 [inline]
 hci_cmd_sync_alloc net/bluetooth/hci_sync.c:55 [inline]
 hci_cmd_sync_add net/bluetooth/hci_sync.c:96 [inline]
 __hci_cmd_sync_sk+0x1d1/0xcf0 net/bluetooth/hci_sync.c:158
 __hci_cmd_sync_status_sk net/bluetooth/hci_sync.c:253 [inline]
 __hci_cmd_sync_status net/bluetooth/hci_sync.c:277 [inline]
 hci_read_local_features_sync net/bluetooth/hci_sync.c:3621 [inline]
 hci_init_stage_sync net/bluetooth/hci_sync.c:3532 [inline]
 hci_init1_sync net/bluetooth/hci_sync.c:3716 [inline]
 hci_init_sync net/bluetooth/hci_sync.c:4798 [inline]
 hci_dev_init_sync net/bluetooth/hci_sync.c:4989 [inline]
 hci_dev_open_sync+0x13a7/0x3260 net/bluetooth/hci_sync.c:5069
 hci_dev_do_open net/bluetooth/hci_core.c:439 [inline]
 hci_power_on+0x195/0x5c0 net/bluetooth/hci_core.c:945
 process_one_work+0x71f/0xc40 kernel/workqueue.c:2302
 worker_thread+0xa29/0x11f0 kernel/workqueue.c:2449
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff8881436e23c0
 which belongs to the cache skbuff_head_cache of size 256
The buggy address is located 232 bytes inside of
 256-byte region [ffff8881436e23c0, ffff8881436e24c0)

The buggy address belongs to the physical page:
page:ffffea00050db880 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1436e2
flags: 0x4000000000000200(slab|zone=1)
raw: 4000000000000200 ffffea0004571780 dead000000000004 ffff888100b9d200
raw: 0000000000000000 00000000800c000c 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 2035, tgid 2035 (udevd), ts 178615994283, free_ts 178608010867
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2643
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2650
 get_page_from_freelist+0x2c7b/0x2cf0 mm/page_alloc.c:4554
 __alloc_pages+0x1c3/0x450 mm/page_alloc.c:5868
 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
 allocate_slab mm/slub.c:1962 [inline]
 new_slab+0x98/0x3d0 mm/slub.c:2015
 ___slab_alloc+0x6f6/0xb50 mm/slub.c:3203
 __slab_alloc+0x5e/0xa0 mm/slub.c:3302
 slab_alloc_node mm/slub.c:3387 [inline]
 kmem_cache_alloc_node+0x1c2/0x340 mm/slub.c:3468
 __alloc_skb+0xea/0x4b0 net/core/skbuff.c:508
 alloc_skb include/linux/skbuff.h:1290 [inline]
 netlink_alloc_large_skb net/netlink/af_netlink.c:1183 [inline]
 netlink_sendmsg+0x626/0xbc0 net/netlink/af_netlink.c:1848
 sock_sendmsg_nosec net/socket.c:716 [inline]
 __sock_sendmsg net/socket.c:728 [inline]
 ____sys_sendmsg+0x5a9/0x990 net/socket.c:2509
 ___sys_sendmsg+0x21c/0x290 net/socket.c:2563
 __sys_sendmsg net/socket.c:2592 [inline]
 __do_sys_sendmsg net/socket.c:2601 [inline]
 __se_sys_sendmsg net/socket.c:2599 [inline]
 __x64_sys_sendmsg+0x1f0/0x2c0 net/socket.c:2599
 x64_sys_call+0x171/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1551 [inline]
 free_pcp_prepare mm/page_alloc.c:1625 [inline]
 free_unref_page_prepare+0x742/0x750 mm/page_alloc.c:3589
 free_unref_page+0x8f/0x530 mm/page_alloc.c:3687
 free_the_page mm/page_alloc.c:836 [inline]
 __free_pages+0x67/0x100 mm/page_alloc.c:5957
 free_pages+0x82/0x90 mm/page_alloc.c:5968
 tlb_batch_list_free mm/mmu_gather.c:75 [inline]
 tlb_finish_mmu+0x2ba/0x370 mm/mmu_gather.c:364
 exit_mmap+0x3dd/0xb60 mm/mmap.c:3378
 __mmput+0x93/0x320 kernel/fork.c:1300
 mmput+0x4b/0x150 kernel/fork.c:1323
 exit_mm kernel/exit.c:568 [inline]
 do_exit+0x981/0x2650 kernel/exit.c:873
 do_group_exit+0x210/0x2d0 kernel/exit.c:1028
 get_signal+0x13b5/0x1520 kernel/signal.c:2889
 arch_do_signal_or_restart+0xb0/0x1030 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x7a/0xb0 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0x5a/0xa0 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:87

Memory state around the buggy address:
 ffff8881436e2380: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
 ffff8881436e2400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881436e2480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                                  ^
 ffff8881436e2500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881436e2580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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