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BUG: KASAN: use-after-free in __nft_trace_packet+0x135/0x150 net/netfilter/nf_tables_core.c:30
Read of size 2 at addr ffff8880563491c0 by task syz.4.315/5411

CPU: 1 PID: 5411 Comm: syz.4.315 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 __nft_trace_packet+0x135/0x150 net/netfilter/nf_tables_core.c:30
 nft_trace_verdict net/netfilter/nf_tables_core.c:110 [inline]
 nft_do_chain+0x12a5/0x14f0 net/netfilter/nf_tables_core.c:256
 nft_do_chain_inet+0x25c/0x340 net/netfilter/nft_chain_filter.c:161
 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline]
 nf_hook_slow+0xb9/0x200 net/netfilter/core.c:584
 nf_hook include/linux/netfilter.h:257 [inline]
 NF_HOOK+0x1f2/0x390 include/linux/netfilter.h:300
 NF_HOOK+0x303/0x390 include/linux/netfilter.h:302
 __netif_receive_skb_one_core net/core/dev.c:5551 [inline]
 __netif_receive_skb+0xcc/0x290 net/core/dev.c:5665
 netif_receive_skb_internal net/core/dev.c:5751 [inline]
 netif_receive_skb+0x19e/0x700 net/core/dev.c:5810
 tun_rx_batched+0x5fb/0x760 drivers/net/tun.c:-1
 tun_get_user+0x2517/0x3a70 drivers/net/tun.c:1989
 tun_chr_write_iter+0x112/0x1e0 drivers/net/tun.c:2019
 call_write_iter include/linux/fs.h:2173 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x745/0xd60 fs/read_write.c:594
 ksys_write+0x152/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f91751aefce
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:00007f9173447fb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f91734486c0 RCX: 00007f91751aefce
RDX: 0000000000000036 RSI: 00002000000002c0 RDI: 00000000000000c8
RBP: 00007f9175284bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9175468038 R14: 00007f9175467fa0 R15: 00007fff10d41358
 </TASK>

Allocated by task 5411:
 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+0x9c/0xd0 mm/kasan/common.c:467
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x100/0x290 mm/slub.c:3238
 __build_skb+0x26/0x2e0 net/core/skbuff.c:241
 build_skb+0x1e/0x170 net/core/skbuff.c:258
 __tun_build_skb+0x32/0x240 drivers/net/tun.c:1589
 tun_build_skb drivers/net/tun.c:1674 [inline]
 tun_get_user+0x19f7/0x3a70 drivers/net/tun.c:1797
 tun_chr_write_iter+0x112/0x1e0 drivers/net/tun.c:2019
 call_write_iter include/linux/fs.h:2173 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x745/0xd60 fs/read_write.c:594
 ksys_write+0x152/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Freed by task 5411:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kmem_cache_free+0x8f/0x210 mm/slub.c:3520
 nft_synproxy_eval_v4+0x34f/0x4e0 net/netfilter/nft_synproxy.c:60
 nft_synproxy_do_eval+0x304/0x570 net/netfilter/nft_synproxy.c:141
 expr_call_ops_eval net/netfilter/nf_tables_core.c:198 [inline]
 nft_do_chain+0x48c/0x14f0 net/netfilter/nf_tables_core.c:238
 nft_do_chain_inet+0x25c/0x340 net/netfilter/nft_chain_filter.c:161
 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline]
 nf_hook_slow+0xb9/0x200 net/netfilter/core.c:584
 nf_hook include/linux/netfilter.h:257 [inline]
 NF_HOOK+0x1f2/0x390 include/linux/netfilter.h:300
 NF_HOOK+0x303/0x390 include/linux/netfilter.h:302
 __netif_receive_skb_one_core net/core/dev.c:5551 [inline]
 __netif_receive_skb+0xcc/0x290 net/core/dev.c:5665
 netif_receive_skb_internal net/core/dev.c:5751 [inline]
 netif_receive_skb+0x19e/0x700 net/core/dev.c:5810
 tun_rx_batched+0x5fb/0x760 drivers/net/tun.c:-1
 tun_get_user+0x2517/0x3a70 drivers/net/tun.c:1989
 tun_chr_write_iter+0x112/0x1e0 drivers/net/tun.c:2019
 call_write_iter include/linux/fs.h:2173 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x745/0xd60 fs/read_write.c:594
 ksys_write+0x152/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff888056349140
 which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 128 bytes inside of
 232-byte region [ffff888056349140, ffff888056349228)
The buggy address belongs to the page:
page:ffffea000158d240 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888056349780 pfn:0x56349
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea0000a9ea48 ffffea00008f9308 ffff88801bbe7140
raw: ffff888056349780 00000000000c000b 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 0x112a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_HARDWALL), pid 4613, ts 98350873989, free_ts 97960191458
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x1bbd/0x1ca0 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 alloc_slab_page mm/slub.c:1780 [inline]
 allocate_slab mm/slub.c:1917 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1980
 ___slab_alloc+0x80a/0xdd0 mm/slub.c:3013
 __slab_alloc mm/slub.c:3100 [inline]
 slab_alloc_node mm/slub.c:3191 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x195/0x290 mm/slub.c:3238
 skb_clone+0x1bd/0x350 net/core/skbuff.c:1523
 dev_queue_xmit_nit+0x2cc/0xb00 net/core/dev.c:2354
 xmit_one net/core/dev.c:3657 [inline]
 dev_hard_start_xmit+0x13e/0x7e0 net/core/dev.c:3678
 sch_direct_xmit+0x25a/0x4b0 net/sched/sch_generic.c:345
 __dev_xmit_skb net/core/dev.c:3897 [inline]
 __dev_queue_xmit+0x179f/0x2f80 net/core/dev.c:4266
 neigh_hh_output include/net/neighbour.h:493 [inline]
 neigh_output include/net/neighbour.h:507 [inline]
 ip_finish_output2+0xc87/0x10a0 net/ipv4/ip_output.c:228
 NF_HOOK_COND include/linux/netfilter.h:291 [inline]
 ip_output+0x2c0/0x3e0 net/ipv4/ip_output.c:434
 dst_output include/net/dst.h:452 [inline]
 ip_local_out net/ipv4/ip_output.c:126 [inline]
 __ip_queue_xmit+0x11c1/0x1c00 net/ipv4/ip_output.c:538
 __tcp_transmit_skb+0x1d11/0x3200 net/ipv4/tcp_output.c:1404
 tcp_transmit_skb net/ipv4/tcp_output.c:1422 [inline]
 tcp_write_xmit+0x18d3/0x6580 net/ipv4/tcp_output.c:2718
 __tcp_push_pending_frames+0x92/0x250 net/ipv4/tcp_output.c:2903
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page_list+0x119/0x820 mm/page_alloc.c:3433
 release_pages+0x186c/0x1be0 mm/swap.c:963
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:240 [inline]
 tlb_flush_mmu mm/mmu_gather.c:247 [inline]
 tlb_finish_mmu+0x176/0x300 mm/mmu_gather.c:338
 exit_mmap+0x3d0/0x640 mm/mmap.c:3218
 __mmput+0x115/0x3b0 kernel/fork.c:1127
 exit_mm+0x588/0x6e0 kernel/exit.c:550
 do_exit+0x5a9/0x20c0 kernel/exit.c:870
 __do_sys_exit kernel/exit.c:966 [inline]
 __se_sys_exit kernel/exit.c:964 [inline]
 __x64_sys_exit+0x3c/0x40 kernel/exit.c:964
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Memory state around the buggy address:
 ffff888056349080: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
 ffff888056349100: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
>ffff888056349180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888056349200: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
 ffff888056349280: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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