==================================================================
BUG: KASAN: slab-use-after-free in skb_network_header include/linux/skbuff.h:2952 [inline]
BUG: KASAN: slab-use-after-free in ipv6_hdr include/linux/ipv6.h:101 [inline]
BUG: KASAN: slab-use-after-free in nf_nat_ipv6_in+0x141/0x2c0 net/netfilter/nf_nat_proto.c:949
Read of size 8 at addr ffff888040ea9490 by task syz.0.1449/12817

CPU: 1 PID: 12817 Comm: syz.0.1449 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 skb_network_header include/linux/skbuff.h:2952 [inline]
 ipv6_hdr include/linux/ipv6.h:101 [inline]
 nf_nat_ipv6_in+0x141/0x2c0 net/netfilter/nf_nat_proto.c:949
 nf_hook_entry_hookfn include/linux/netfilter.h:156 [inline]
 nf_hook_slow+0xb9/0x210 net/netfilter/core.c:626
 nf_hook include/linux/netfilter.h:271 [inline]
 NF_HOOK include/linux/netfilter.h:314 [inline]
 br_nf_pre_routing_ipv6+0x55b/0x6a0 net/bridge/br_netfilter_ipv6.c:184
 nf_hook_entry_hookfn include/linux/netfilter.h:156 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:277 [inline]
 br_handle_frame+0x12fa/0x15b0 net/bridge/br_input.c:433
 __netif_receive_skb_core+0xf94/0x3ac0 net/core/dev.c:5604
 __netif_receive_skb_one_core net/core/dev.c:5708 [inline]
 __netif_receive_skb+0x74/0x290 net/core/dev.c:5824
 netif_receive_skb_internal net/core/dev.c:5910 [inline]
 netif_receive_skb+0x1bc/0x720 net/core/dev.c:5969
 tun_rx_batched+0x1df/0x790 drivers/net/tun.c:1561
 tun_get_user+0x286c/0x3d30 drivers/net/tun.c:2020
 tun_chr_write_iter+0x119/0x200 drivers/net/tun.c:2066
 call_write_iter include/linux/fs.h:2019 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x474/0x9a0 fs/read_write.c:584
 ksys_write+0x151/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f3cbbf6980e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007f3cbcf25fb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f3cbcf266c0 RCX: 00007f3cbbf6980e
RDX: 000000000000007e RSI: 00002000000028c0 RDI: 00000000000000c8
RBP: 00007f3cbc037fed R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3cbc226038 R14: 00007f3cbc225fa0 R15: 00007ffd92317ac8
 </TASK>

Allocated by task 12817:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:770
 slab_alloc_node mm/slub.c:3518 [inline]
 slab_alloc mm/slub.c:3526 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3533 [inline]
 kmem_cache_alloc+0x17e/0x2d0 mm/slub.c:3542
 __build_skb net/core/skbuff.c:451 [inline]
 build_skb+0x29/0x250 net/core/skbuff.c:466
 __tun_build_skb+0x36/0x320 drivers/net/tun.c:1616
 tun_build_skb drivers/net/tun.c:1707 [inline]
 tun_get_user+0x1cb8/0x3d30 drivers/net/tun.c:1831
 tun_chr_write_iter+0x119/0x200 drivers/net/tun.c:2066
 call_write_iter include/linux/fs.h:2019 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x474/0x9a0 fs/read_write.c:584
 ksys_write+0x151/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 12817:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1833 [inline]
 slab_free_freelist_hook+0x154/0x240 mm/slub.c:1859
 slab_free mm/slub.c:3853 [inline]
 kmem_cache_free+0xf8/0x290 mm/slub.c:3875
 NF_DROP_REASON include/linux/netfilter.h:30 [inline]
 nft_do_chain+0x14d9/0x16d0 net/netfilter/nf_tables_core.c:-1
 nft_nat_do_chain+0x29b/0x380 net/netfilter/nft_chain_nat.c:32
 nf_nat_inet_fn+0x5dd/0xb20 net/netfilter/nf_nat_core.c:958
 nf_nat_ipv6_fn+0x227/0x2e0 net/netfilter/nf_nat_proto.c:937
 nf_nat_ipv6_in+0xf1/0x2c0 net/netfilter/nf_nat_proto.c:947
 nf_hook_entry_hookfn include/linux/netfilter.h:156 [inline]
 nf_hook_slow+0xb9/0x210 net/netfilter/core.c:626
 nf_hook include/linux/netfilter.h:271 [inline]
 NF_HOOK include/linux/netfilter.h:314 [inline]
 br_nf_pre_routing_ipv6+0x55b/0x6a0 net/bridge/br_netfilter_ipv6.c:184
 nf_hook_entry_hookfn include/linux/netfilter.h:156 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:277 [inline]
 br_handle_frame+0x12fa/0x15b0 net/bridge/br_input.c:433
 __netif_receive_skb_core+0xf94/0x3ac0 net/core/dev.c:5604
 __netif_receive_skb_one_core net/core/dev.c:5708 [inline]
 __netif_receive_skb+0x74/0x290 net/core/dev.c:5824
 netif_receive_skb_internal net/core/dev.c:5910 [inline]
 netif_receive_skb+0x1bc/0x720 net/core/dev.c:5969
 tun_rx_batched+0x1df/0x790 drivers/net/tun.c:1561
 tun_get_user+0x286c/0x3d30 drivers/net/tun.c:2020
 tun_chr_write_iter+0x119/0x200 drivers/net/tun.c:2066
 call_write_iter include/linux/fs.h:2019 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x474/0x9a0 fs/read_write.c:584
 ksys_write+0x151/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff888040ea93c0
 which belongs to the cache skbuff_head_cache of size 240
The buggy address is located 208 bytes inside of
 freed 240-byte region [ffff888040ea93c0, ffff888040ea94b0)

The buggy address belongs to the physical page:
page:ffffea000103aa40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x40ea9
flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000800 ffff888020e75640 dead000000000122 0000000000000000
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 0x112820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_HARDWALL), pid 60, tgid 60 (kworker/u4:4), ts 1258638898974, free_ts 1257938649449
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1582
 prep_new_page mm/page_alloc.c:1589 [inline]
 get_page_from_freelist+0x2181/0x22a0 mm/page_alloc.c:3221
 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4501
 alloc_slab_page+0x5d/0x180 mm/slub.c:1903
 allocate_slab mm/slub.c:2050 [inline]
 new_slab+0x87/0x2d0 mm/slub.c:2103
 ___slab_alloc+0xc5c/0x12f0 mm/slub.c:3275
 __slab_alloc mm/slub.c:3361 [inline]
 __slab_alloc_node mm/slub.c:3414 [inline]
 slab_alloc_node mm/slub.c:3508 [inline]
 kmem_cache_alloc_node+0x12e/0x320 mm/slub.c:3563
 __alloc_skb+0x103/0x2c0 net/core/skbuff.c:643
 alloc_skb include/linux/skbuff.h:1316 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline]
 nsim_dev_trap_report_work+0x253/0xa90 drivers/net/netdevsim/dev.c:851
 process_one_work kernel/workqueue.c:2657 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1182 [inline]
 free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366
 free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2505
 release_pages+0x208a/0x2300 mm/swap.c:1022
 tlb_batch_pages_flush mm/mmu_gather.c:99 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:294 [inline]
 tlb_flush_mmu+0x379/0x510 mm/mmu_gather.c:301
 tlb_finish_mmu+0xf4/0x220 mm/mmu_gather.c:425
 exit_mmap+0x428/0xb90 mm/mmap.c:3323
 __mmput+0x118/0x3a0 kernel/fork.c:1365
 exit_mm+0x23f/0x340 kernel/exit.c:576
 do_exit+0x909/0x2530 kernel/exit.c:877
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1032
 get_signal+0x12a6/0x1390 kernel/signal.c:2927
 arch_do_signal_or_restart+0xc2/0x7b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:213
 __syscall_exit_to_user_mode_work kernel/entry/common.c:294 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:305
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82

Memory state around the buggy address:
 ffff888040ea9380: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
 ffff888040ea9400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888040ea9480: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff888040ea9500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888040ea9580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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