netlink: 17 bytes leftover after parsing attributes in process `syz-executor0'.
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BUG: KASAN: null-ptr-deref in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
BUG: KASAN: null-ptr-deref in refcount_sub_and_test_checked+0x9d/0x310 lib/refcount.c:179
Read of size 4 at addr 000000000000002e by task syz-executor0/9626

CPU: 0 PID: 9626 Comm: syz-executor0 Not tainted 4.19.0-rc6+ #245
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
 kasan_report_error mm/kasan/report.c:352 [inline]
 kasan_report.cold.9+0x6d/0x309 mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272
 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
 refcount_sub_and_test_checked+0x9d/0x310 lib/refcount.c:179
 refcount_dec_and_test_checked+0x1a/0x20 lib/refcount.c:212
 ip_fib_metrics_put include/net/ip.h:428 [inline]
 fib6_info_destroy_rcu+0x2ef/0x3e0 net/ipv6/ip6_fib.c:204
 __rcu_reclaim kernel/rcu/rcu.h:236 [inline]
 rcu_do_batch kernel/rcu/tree.c:2576 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2880 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2847 [inline]
 rcu_process_callbacks+0xf23/0x2670 kernel/rcu/tree.c:2864
 __do_softirq+0x30b/0xad8 kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:372 [inline]
 irq_exit+0x17f/0x1c0 kernel/softirq.c:412
 exiting_irq arch/x86/include/asm/apic.h:536 [inline]
 smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1056
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:864
 </IRQ>
RIP: 0010:__read_once_size include/linux/compiler.h:188 [inline]
RIP: 0010:compound_head include/linux/page-flags.h:142 [inline]
RIP: 0010:PageSwapCache include/linux/page-flags.h:338 [inline]
RIP: 0010:free_swap_cache mm/swap_state.c:290 [inline]
RIP: 0010:free_pages_and_swap_cache+0x167/0x6f0 mm/swap_state.c:318
Code: fe ff ff c6 00 00 49 8d 45 08 48 89 85 40 fe ff ff 48 c1 e8 03 80 3c 18 00 0f 85 25 05 00 00 48 8b 85 70 fe ff ff 4d 8b 75 08 <80> 38 00 0f 85 00 05 00 00 48 8b 85 70 fe ff ff 4d 89 b7 00 ff ff
RSP: 0018:ffff8801a1abea28 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffffed0034357d5a RBX: dffffc0000000000 RCX: ffffffff81b9d5cd
RDX: 0000000000000000 RSI: ffffffff81b9d29a RDI: 0000000000000004
RBP: ffff8801a1abebf8 R08: ffff880199490600 R09: fffff94000e142ce
R10: fffff94000e142ce R11: ffffea00070a1677 R12: ffffea00070935c0
R13: ffffea0007091000 R14: dead000000000100 R15: ffff8801a1abebd0
 tlb_flush_mmu_free+0xff/0x1b0 mm/memory.c:249
 zap_pte_range mm/memory.c:1405 [inline]
 zap_pmd_range mm/memory.c:1440 [inline]
 zap_pud_range mm/memory.c:1469 [inline]
 zap_p4d_range mm/memory.c:1490 [inline]
 unmap_page_range+0x1873/0x2030 mm/memory.c:1511
 unmap_single_vma+0x19b/0x310 mm/memory.c:1556
 unmap_vmas+0x125/0x200 mm/memory.c:1586
 exit_mmap+0x2be/0x590 mm/mmap.c:3093
 __mmput kernel/fork.c:1001 [inline]
 mmput+0x247/0x610 kernel/fork.c:1022
 exit_mm kernel/exit.c:545 [inline]
 do_exit+0xe6f/0x2610 kernel/exit.c:854
 do_group_exit+0x177/0x440 kernel/exit.c:970
 get_signal+0x8b0/0x1980 kernel/signal.c:2513
 do_signal+0x9c/0x21e0 arch/x86/kernel/signal.c:816
 exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457579
Code: 1d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fe398d8ccf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000000 RBX: 000000000072bf08 RCX: 0000000000457579
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000072bf08
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000072bf0c
R13: 00007ffdb066896f R14: 00007fe398d8d9c0 R15: 0000000000000000
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