================================================================== BUG: KASAN: use-after-free in __nft_trace_packet+0x135/0x150 net/netfilter/nf_tables_core.c:30 Read of size 2 at addr ffff88801afb9440 by task syz.2.32/4527 CPU: 1 PID: 4527 Comm: syz.2.32 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x168/0x230 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+0x120e/0x1420 net/netfilter/nf_tables_core.c:256 nft_do_chain_inet+0x22b/0x300 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+0x1cb/0x360 include/linux/netfilter.h:300 NF_HOOK+0x2d6/0x360 include/linux/netfilter.h:302 __netif_receive_skb_one_core net/core/dev.c:5525 [inline] __netif_receive_skb+0xcc/0x290 net/core/dev.c:5639 netif_receive_skb_internal net/core/dev.c:5725 [inline] netif_receive_skb+0x19e/0x6c0 net/core/dev.c:5784 tun_rx_batched+0x5a1/0x6d0 drivers/net/tun.c:-1 tun_get_user+0x23f0/0x38d0 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+0x712/0xd00 fs/read_write.c:594 ksys_write+0x14d/0x250 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: 0033:0x7f6de5a261ff Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48 RSP: 002b:00007f6de3c8e000 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f6de5c7dfa0 RCX: 00007f6de5a261ff RDX: 0000000000000036 RSI: 00002000000001c0 RDI: 00000000000000c8 RBP: 00007f6de5aabf91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000036 R11: 0000000000000293 R12: 0000000000000000 R13: 00007f6de5c7e038 R14: 00007f6de5c7dfa0 R15: 00007fffcaafeb88 Allocated by task 4527: 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+0x18f1/0x38d0 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+0x712/0xd00 fs/read_write.c:594 ksys_write+0x14d/0x250 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 4527: 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+0x373/0x560 net/netfilter/nft_synproxy.c:60 nft_synproxy_do_eval+0x341/0x570 net/netfilter/nft_synproxy.c:141 expr_call_ops_eval net/netfilter/nf_tables_core.c:198 [inline] nft_do_chain+0x3fc/0x1420 net/netfilter/nf_tables_core.c:238 nft_do_chain_inet+0x22b/0x300 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+0x1cb/0x360 include/linux/netfilter.h:300 NF_HOOK+0x2d6/0x360 include/linux/netfilter.h:302 __netif_receive_skb_one_core net/core/dev.c:5525 [inline] __netif_receive_skb+0xcc/0x290 net/core/dev.c:5639 netif_receive_skb_internal net/core/dev.c:5725 [inline] netif_receive_skb+0x19e/0x6c0 net/core/dev.c:5784 tun_rx_batched+0x5a1/0x6d0 drivers/net/tun.c:-1 tun_get_user+0x23f0/0x38d0 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+0x712/0xd00 fs/read_write.c:594 ksys_write+0x14d/0x250 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 ffff88801afb93c0 which belongs to the cache skbuff_head_cache of size 232 The buggy address is located 128 bytes inside of 232-byte region [ffff88801afb93c0, ffff88801afb94a8) The buggy address belongs to the page: page:ffffea00006bee40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1afb9 flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 ffffea000088e400 0000000900000009 ffff888144bf3140 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 0x112a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_HARDWALL), pid 4304, ts 71723561679, free_ts 69771653761 prep_new_page mm/page_alloc.c:2426 [inline] get_page_from_freelist+0x1b77/0x1c60 mm/page_alloc.c:4192 __alloc_pages+0x1e1/0x470 mm/page_alloc.c:5487 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+0x81e/0xdf0 mm/slub.c:3013 __slab_alloc mm/slub.c:3100 [inline] slab_alloc_node mm/slub.c:3191 [inline] kmem_cache_alloc_node+0x1c3/0x2d0 mm/slub.c:3261 __alloc_skb+0xf4/0x750 net/core/skbuff.c:415 alloc_skb include/linux/skbuff.h:1162 [inline] nlmsg_new include/net/netlink.h:953 [inline] inet6_rt_notify+0xdd/0x290 net/ipv6/route.c:6181 fib6_del_route net/ipv6/ip6_fib.c:1996 [inline] fib6_del+0x1082/0x1500 net/ipv6/ip6_fib.c:2031 fib6_clean_node+0x296/0x580 net/ipv6/ip6_fib.c:2193 fib6_walk_continue+0x640/0x8c0 net/ipv6/ip6_fib.c:2115 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2163 fib6_clean_tree net/ipv6/ip6_fib.c:2243 [inline] __fib6_clean_all+0x20e/0x350 net/ipv6/ip6_fib.c:2259 rt6_sync_down_dev net/ipv6/route.c:4915 [inline] rt6_disable_ip+0x11f/0x690 net/ipv6/route.c:4920 addrconf_ifdown+0x149/0x1970 net/ipv6/addrconf.c:3775 addrconf_notify+0x445/0xf00 net/ipv6/addrconf.c:-1 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391 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+0x94/0x280 mm/page_alloc.c:3396 free_slab mm/slub.c:2020 [inline] discard_slab mm/slub.c:2026 [inline] __unfreeze_partials+0x1a5/0x200 mm/slub.c:2512 put_cpu_partial+0x12d/0x190 mm/slub.c:2592 qlist_free_all+0x35/0x90 mm/kasan/quarantine.c:176 kasan_quarantine_reduce+0x150/0x160 mm/kasan/quarantine.c:283 __kasan_slab_alloc+0x2f/0xd0 mm/kasan/common.c:444 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 kmem_cache_zalloc include/linux/slab.h:728 [inline] ext4_mb_new_blocks+0x53c/0x4940 fs/ext4/mballoc.c:5748 ext4_ext_map_blocks+0x191a/0x6650 fs/ext4/extents.c:4341 ext4_map_blocks+0x981/0x1b30 fs/ext4/inode.c:673 mpage_map_one_extent fs/ext4/inode.c:2408 [inline] mpage_map_and_submit_extent fs/ext4/inode.c:2461 [inline] ext4_writepages+0x12ca/0x2d20 fs/ext4/inode.c:2829 do_writepages+0x48d/0x6d0 mm/page-writeback.c:2386 __writeback_single_inode+0x153/0xda0 fs/fs-writeback.c:1657 writeback_sb_inodes+0x9fe/0x1610 fs/fs-writeback.c:1940 Memory state around the buggy address: ffff88801afb9300: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc ffff88801afb9380: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb >ffff88801afb9400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88801afb9480: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc ffff88801afb9500: fa fb fb fb fb fb 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