syzbot

==================================================================
BUG: KASAN: slab-use-after-free in hci_uart_write_work+0x81c/0x950 drivers/bluetooth/hci_ldisc.c:165
Read of size 4 at addr ffff888073b0e2f0 by task kworker/0:2/118

CPU: 0 UID: 0 PID: 118 Comm: kworker/0:2 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026
Workqueue: events hci_uart_write_work
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x156/0x4c9 mm/kasan/report.c:482
 kasan_report+0xdf/0x1a0 mm/kasan/report.c:595
 hci_uart_write_work+0x81c/0x950 drivers/bluetooth/hci_ldisc.c:165
 process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 worker_thread+0x5da/0xe40 kernel/workqueue.c:3421
 kthread+0x3b3/0x730 kernel/kthread.c:463
 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>

Allocated by task 118:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 kmem_cache_alloc_node_noprof+0x303/0x880 mm/slub.c:5315
 __alloc_skb+0x156/0x410 net/core/skbuff.c:679
 alloc_skb include/linux/skbuff.h:1383 [inline]
 bcsp_prepare_pkt+0xe0/0xa90 drivers/bluetooth/hci_bcsp.c:218
 bcsp_dequeue+0x237/0x4b0 drivers/bluetooth/hci_bcsp.c:308
 hci_uart_dequeue drivers/bluetooth/hci_ldisc.c:107 [inline]
 hci_uart_write_work+0x4d9/0x950 drivers/bluetooth/hci_ldisc.c:161
 process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 worker_thread+0x5da/0xe40 kernel/workqueue.c:3421
 kthread+0x3b3/0x730 kernel/kthread.c:463
 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

The buggy address belongs to the object at ffff888073b0e280
 which belongs to the cache skbuff_head_cache of size 240
The buggy address is located 112 bytes inside of
 freed 240-byte region [ffff888073b0e280, ffff888073b0e370)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x73b0e
ksm flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801e6ac8c0 ffffea0001ceccc0 0000000000000003
raw: 0000000000000000 00000000800c000c 00000000f5000000 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 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5742, tgid 5742 (sshd-session), ts 52751848685, free_ts 52648047880
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1e1/0x250 mm/page_alloc.c:1884
 prep_new_page mm/page_alloc.c:1892 [inline]
 get_page_from_freelist+0xe3d/0x2e10 mm/page_alloc.c:3945
 __alloc_frozen_pages_noprof+0x26c/0x2410 mm/page_alloc.c:5240
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2486
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab mm/slub.c:3248 [inline]
 new_slab+0x2c4/0x440 mm/slub.c:3302
 ___slab_alloc+0xda3/0x1ca0 mm/slub.c:4656
 __slab_alloc.isra.0+0x63/0x110 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5251 [inline]
 kmem_cache_alloc_noprof+0x4ec/0x780 mm/slub.c:5270
 skb_clone+0x190/0x400 net/core/skbuff.c:2087
 dev_queue_xmit_nit+0x255/0xa60 net/core/dev.c:2568
 xmit_one net/core/dev.c:3862 [inline]
 dev_hard_start_xmit+0x2fb/0x6c0 net/core/dev.c:3882
 sch_direct_xmit+0x1b2/0xc60 net/sched/sch_generic.c:347
 __dev_xmit_skb net/core/dev.c:4182 [inline]
 __dev_queue_xmit+0x24bd/0x46f0 net/core/dev.c:4798
 dev_queue_xmit include/linux/netdevice.h:3381 [inline]
 neigh_hh_output include/net/neighbour.h:540 [inline]
 neigh_output include/net/neighbour.h:554 [inline]
 ip_finish_output2+0xf34/0x24b0 net/ipv4/ip_output.c:237
 __ip_finish_output.part.0+0x444/0x6f0 net/ipv4/ip_output.c:315
 __ip_finish_output net/ipv4/ip_output.c:303 [inline]
 ip_finish_output net/ipv4/ip_output.c:325 [inline]
 NF_HOOK_COND include/linux/netfilter.h:307 [inline]
 ip_output+0x39b/0xec0 net/ipv4/ip_output.c:438
page last free pid 5746 tgid 5746 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0x822/0x1130 mm/page_alloc.c:2973
 __folio_put+0x3b4/0x540 mm/swap.c:112
 folio_put include/linux/mm.h:1616 [inline]
 put_page include/linux/mm.h:1685 [inline]
 anon_pipe_put_page fs/pipe.c:139 [inline]
 anon_pipe_buf_release+0x40c/0x530 fs/pipe.c:147
 pipe_buf_release include/linux/pipe_fs_i.h:273 [inline]
 pipe_update_tail fs/pipe.c:242 [inline]
 anon_pipe_read+0x5cd/0x1200 fs/pipe.c:361
 new_sync_read fs/read_write.c:491 [inline]
 vfs_read+0x957/0xb30 fs/read_write.c:572
 ksys_read+0x1f8/0x250 fs/read_write.c:715
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888073b0e180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888073b0e200: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
>ffff888073b0e280: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                             ^
 ffff888073b0e300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
 ffff888073b0e380: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
==================================================================