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BUG: KASAN: use-after-free in h4_recv_buf+0x946/0xd50 drivers/bluetooth/hci_h4.c:199
Read of size 2 at addr ffff888027f8bdea by task kworker/u4:6/4475

CPU: 0 PID: 4475 Comm: kworker/u4:6 Not tainted 5.14.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound flush_to_ldisc
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1ae/0x29f lib/dump_stack.c:105
 print_address_description+0x66/0x3b0 mm/kasan/report.c:233
 __kasan_report mm/kasan/report.c:419 [inline]
 kasan_report+0x163/0x210 mm/kasan/report.c:436
 h4_recv_buf+0x946/0xd50 drivers/bluetooth/hci_h4.c:199
 h4_recv+0xf4/0x1b0 drivers/bluetooth/hci_h4.c:115
 hci_uart_tty_receive+0x1d2/0x4a0 drivers/bluetooth/hci_ldisc.c:613
 tty_ldisc_receive_buf+0x128/0x170 drivers/tty/tty_buffer.c:475
 tty_port_default_receive_buf+0x6a/0x90 drivers/tty/tty_port.c:39
 receive_buf drivers/tty/tty_buffer.c:491 [inline]
 flush_to_ldisc+0x2f2/0x510 drivers/tty/tty_buffer.c:543
 process_one_work+0x833/0x10c0 kernel/workqueue.c:2276
 worker_thread+0xac1/0x1320 kernel/workqueue.c:2422
 kthread+0x453/0x480 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Allocated by task 1258:
 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_slab_alloc+0x96/0xd0 mm/kasan/common.c:467
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook mm/slab.h:519 [inline]
 slab_alloc_node mm/slub.c:2959 [inline]
 kmem_cache_alloc_node+0x200/0x370 mm/slub.c:2995
 __alloc_skb+0xd8/0x580 net/core/skbuff.c:414
 alloc_skb include/linux/skbuff.h:1112 [inline]
 bt_skb_alloc include/net/bluetooth/bluetooth.h:389 [inline]
 h4_recv_buf+0x274/0xd50 drivers/bluetooth/hci_h4.c:181
 h4_recv+0xf4/0x1b0 drivers/bluetooth/hci_h4.c:115
 hci_uart_tty_receive+0x1d2/0x4a0 drivers/bluetooth/hci_ldisc.c:613
 tiocsti drivers/tty/tty_io.c:2311 [inline]
 tty_ioctl+0xde5/0x1720 drivers/tty/tty_io.c:2719
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 2026:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x3d/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0x109/0x150 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1628 [inline]
 slab_free_freelist_hook+0x1d8/0x290 mm/slub.c:1653
 slab_free mm/slub.c:3213 [inline]
 kmem_cache_free+0x85/0x170 mm/slub.c:3229
 hci_event_packet+0x1238/0x1bd0 net/bluetooth/hci_event.c:6400
 hci_rx_work+0x229/0x410 net/bluetooth/hci_core.c:5120
 process_one_work+0x833/0x10c0 kernel/workqueue.c:2276
 worker_thread+0xac1/0x1320 kernel/workqueue.c:2422
 kthread+0x453/0x480 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff888027f8bdc0
 which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 42 bytes inside of
 232-byte region [ffff888027f8bdc0, ffff888027f8bea8)
The buggy address belongs to the page:
page:ffffea00009fe2c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x27f8b
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 0000000000000000 0000000800000001 ffff8880161bd140
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 0x12a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY), pid 8431, ts 61827787219, free_ts 38675235800
 prep_new_page mm/page_alloc.c:2436 [inline]
 get_page_from_freelist+0x779/0xa30 mm/page_alloc.c:4169
 __alloc_pages+0x26c/0x5f0 mm/page_alloc.c:5391
 alloc_slab_page mm/slub.c:1691 [inline]
 allocate_slab+0xf1/0x540 mm/slub.c:1831
 new_slab mm/slub.c:1894 [inline]
 new_slab_objects mm/slub.c:2640 [inline]
 ___slab_alloc+0x1cf/0x350 mm/slub.c:2803
 __slab_alloc mm/slub.c:2843 [inline]
 slab_alloc_node mm/slub.c:2925 [inline]
 slab_alloc mm/slub.c:2967 [inline]
 kmem_cache_alloc+0x299/0x340 mm/slub.c:2972
 __build_skb+0x25/0x2f0 net/core/skbuff.c:240
 build_skb+0x1f/0x170 net/core/skbuff.c:257
 page_to_skb+0x145/0xbb0 drivers/net/virtio_net.c:432
 receive_mergeable+0xab1/0x3940 drivers/net/virtio_net.c:1031
 receive_buf+0x158/0x1d90 drivers/net/virtio_net.c:1141
 virtnet_receive drivers/net/virtio_net.c:1433 [inline]
 virtnet_poll+0x5bb/0x11a0 drivers/net/virtio_net.c:1542
 __napi_poll+0xba/0x4f0 net/core/dev.c:7047
 napi_poll net/core/dev.c:7114 [inline]
 net_rx_action+0x62c/0xf30 net/core/dev.c:7201
 __do_softirq+0x372/0x783 kernel/softirq.c:558
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x21b/0x260 kernel/softirq.c:636
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:648
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1346 [inline]
 free_pcp_prepare+0xc29/0xd20 mm/page_alloc.c:1397
 free_unref_page_prepare mm/page_alloc.c:3332 [inline]
 free_unref_page+0x7e/0x550 mm/page_alloc.c:3411
 free_slab mm/slub.c:1934 [inline]
 discard_slab mm/slub.c:1940 [inline]
 __slab_free+0x5c0/0x6b0 mm/slub.c:3143
 do_slab_free mm/slub.c:3201 [inline]
 ___cache_free+0xfc/0x120 mm/slub.c:3220
 qlist_free_all mm/kasan/quarantine.c:165 [inline]
 kasan_quarantine_reduce+0x151/0x1c0 mm/kasan/quarantine.c:272
 __kasan_slab_alloc+0x2f/0xd0 mm/kasan/common.c:444
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook mm/slab.h:519 [inline]
 slab_alloc_node mm/slub.c:2959 [inline]
 slab_alloc mm/slub.c:2967 [inline]
 kmem_cache_alloc+0x1d1/0x340 mm/slub.c:2972
 getname_flags+0xba/0x640 fs/namei.c:138
 user_path_at_empty+0x28/0x50 fs/namei.c:2747
 user_path_at include/linux/namei.h:57 [inline]
 vfs_statx+0x102/0x3d0 fs/stat.c:203
 vfs_fstatat fs/stat.c:225 [inline]
 vfs_lstat include/linux/fs.h:3386 [inline]
 __do_sys_newlstat fs/stat.c:380 [inline]
 __se_sys_newlstat+0xab/0x770 fs/stat.c:374
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Memory state around the buggy address:
 ffff888027f8bc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888027f8bd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
>ffff888027f8bd80: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
                                                          ^
 ffff888027f8be00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888027f8be80: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
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