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BUG: KMSAN: use-after-free in skb_unref include/linux/skbuff.h:1011 [inline]
BUG: KMSAN: use-after-free in kfree_skb+0x23c/0x4c0 net/core/skbuff.c:693
CPU: 1 PID: 11428 Comm: syz-executor.0 Not tainted 5.4.0-rc5+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x191/0x1f0 lib/dump_stack.c:113
 kmsan_report+0x128/0x220 mm/kmsan/kmsan_report.c:108
 __msan_warning+0x73/0xe0 mm/kmsan/kmsan_instr.c:245
 skb_unref include/linux/skbuff.h:1011 [inline]
 kfree_skb+0x23c/0x4c0 net/core/skbuff.c:693
 bcsp_close+0x127/0x1e0 drivers/bluetooth/hci_bcsp.c:748
 hci_uart_tty_close+0x385/0x410 drivers/bluetooth/hci_ldisc.c:548
 tty_ldisc_close drivers/tty/tty_ldisc.c:494 [inline]
 tty_ldisc_kill drivers/tty/tty_ldisc.c:642 [inline]
 tty_ldisc_release+0x5dd/0xd50 drivers/tty/tty_ldisc.c:814
 tty_release_struct+0x4f/0x1d0 drivers/tty/tty_io.c:1612
 tty_release+0x1be2/0x1e80 drivers/tty/tty_io.c:1785
 __fput+0x4c9/0xba0 fs/file_table.c:280
 ____fput+0x37/0x40 fs/file_table.c:313
 task_work_run+0x22e/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:163 [inline]
 prepare_exit_to_usermode+0x39d/0x4d0 arch/x86/entry/common.c:194
 syscall_return_slowpath+0x90/0x610 arch/x86/entry/common.c:274
 do_syscall_64+0xdc/0x160 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x413ae1
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007ffebaf215f0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000006 RCX: 0000000000413ae1
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 0000000000000001 R08: ffffffffffffffff R09: ffffffffffffffff
R10: 00007ffebaf216d0 R11: 0000000000000293 R12: 000000000075c9a0
R13: 000000000075c9a0 R14: 0000000000760320 R15: 000000000075bfd4

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:151 [inline]
 kmsan_internal_poison_shadow+0x60/0x120 mm/kmsan/kmsan.c:134
 kmsan_slab_free+0x8d/0xf0 mm/kmsan/kmsan_hooks.c:108
 slab_free_freelist_hook mm/slub.c:1473 [inline]
 slab_free mm/slub.c:3047 [inline]
 kmem_cache_free+0x2d1/0x2b70 mm/slub.c:3063
 kfree_skbmem net/core/skbuff.c:644 [inline]
 __kfree_skb net/core/skbuff.c:680 [inline]
 kfree_skb+0x473/0x4c0 net/core/skbuff.c:697
 hsr_forward_skb+0x1e9/0x3070 net/hsr/hsr_forward.c:378
 hsr_dev_xmit+0xf8/0x160 net/hsr/hsr_device.c:231
 __netdev_start_xmit include/linux/netdevice.h:4420 [inline]
 netdev_start_xmit include/linux/netdevice.h:4434 [inline]
 xmit_one net/core/dev.c:3280 [inline]
 dev_hard_start_xmit+0x51a/0xab0 net/core/dev.c:3296
 __dev_queue_xmit+0x35b6/0x4200 net/core/dev.c:3873
 dev_queue_xmit+0x4b/0x60 net/core/dev.c:3906
 neigh_connected_output+0x66f/0x6f0 net/core/neighbour.c:1519
 neigh_output include/net/neighbour.h:511 [inline]
 ip6_finish_output2+0x2129/0x2670 net/ipv6/ip6_output.c:116
 __ip6_finish_output+0x83d/0x8f0 net/ipv6/ip6_output.c:142
 ip6_finish_output+0x2db/0x420 net/ipv6/ip6_output.c:152
 NF_HOOK_COND include/linux/netfilter.h:294 [inline]
 ip6_output+0x5d3/0x720 net/ipv6/ip6_output.c:175
 dst_output include/net/dst.h:436 [inline]
 NF_HOOK include/linux/netfilter.h:305 [inline]
 mld_sendpack+0xebd/0x13d0 net/ipv6/mcast.c:1682
 mld_send_initial_cr+0x450/0x4d0 net/ipv6/mcast.c:2099
 mld_dad_timer_expire+0x4d/0x550 net/ipv6/mcast.c:2118
 call_timer_fn+0x232/0x530 kernel/time/timer.c:1404
 expire_timers kernel/time/timer.c:1449 [inline]
 __run_timers+0xd60/0x1270 kernel/time/timer.c:1773
 run_timer_softirq+0x2d/0x50 kernel/time/timer.c:1786
 __do_softirq+0x4a1/0x83a kernel/softirq.c:293
 invoke_softirq kernel/softirq.c:375 [inline]
 irq_exit+0x230/0x280 kernel/softirq.c:416
 exiting_irq+0xe/0x10 arch/x86/include/asm/apic.h:536
 smp_apic_timer_interrupt+0x48/0x70 arch/x86/kernel/apic/apic.c:1139
 apic_timer_interrupt+0x2e/0x40 arch/x86/entry/entry_64.S:837
 native_safe_halt arch/x86/include/asm/irqflags.h:60 [inline]
 arch_safe_halt arch/x86/include/asm/irqflags.h:103 [inline]
 default_idle+0x53/0x90 arch/x86/kernel/process.c:580
 arch_cpu_idle+0x25/0x30 arch/x86/kernel/process.c:571
 default_idle_call kernel/sched/idle.c:94 [inline]
 cpuidle_idle_call kernel/sched/idle.c:154 [inline]
 do_idle+0x1d5/0x780 kernel/sched/idle.c:263
 cpu_startup_entry+0x45/0x50 kernel/sched/idle.c:355
 rest_init+0x1be/0x1f0 init/main.c:452
 arch_call_rest_init+0x13/0x15
 start_kernel+0x987/0xb57 init/main.c:787
 x86_64_start_reservations+0x18/0x2e arch/x86/kernel/head64.c:490
 x86_64_start_kernel+0x81/0x84 arch/x86/kernel/head64.c:471
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241
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