syzbot

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BUG: KASAN: slab-out-of-bounds in fib6_info_nh_dev+0x37/0x310 include/net/nexthop.h:536
Read of size 8 at addr ffff8880346396d0 by task syz.3.9530/9578

CPU: 1 UID: 0 PID: 9578 Comm: syz.3.9530 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 fib6_info_nh_dev+0x37/0x310 include/net/nexthop.h:536
 nft_fib6_info_nh_uses_dev+0xbc/0x150 net/ipv6/netfilter/nft_fib_ipv6.c:174
 nft_fib6_eval+0x88e/0xba0 net/ipv6/netfilter/nft_fib_ipv6.c:231
 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline]
 nft_do_chain+0x45e/0x1990 net/netfilter/nf_tables_core.c:285
 nft_do_chain_inet+0x29d/0x380 net/netfilter/nft_chain_filter.c:162
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_slow+0xc5/0x220 net/netfilter/core.c:622
 nf_hook include/linux/netfilter.h:273 [inline]
 NF_HOOK+0x21f/0x3c0 include/linux/netfilter.h:316
 __netif_receive_skb_one_core net/core/dev.c:6181 [inline]
 __netif_receive_skb net/core/dev.c:6294 [inline]
 netif_receive_skb_internal net/core/dev.c:6380 [inline]
 netif_receive_skb+0x278/0xc50 net/core/dev.c:6439
 tun_rx_batched+0x1de/0x790 drivers/net/tun.c:1485
 tun_get_user+0x2a78/0x3dd0 drivers/net/tun.c:1953
 tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1999
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x61d/0xb90 fs/read_write.c:688
 ksys_write+0x150/0x270 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8f5715cfce
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:00007f8f553f5fb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f8f553f66c0 RCX: 00007f8f5715cfce
RDX: 000000000000007a RSI: 00002000000002c0 RDI: 00000000000000c8
RBP: 00007f8f57232c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8f57416038 R14: 00007f8f57415fa0 R15: 00007ffd3fdee258
 </TASK>

Allocated by task 9098:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5383
 kmalloc_noprof include/linux/slab.h:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 nexthop_alloc net/ipv4/nexthop.c:536 [inline]
 nexthop_create net/ipv4/nexthop.c:2901 [inline]
 nexthop_add net/ipv4/nexthop.c:2968 [inline]
 rtm_new_nexthop+0x28b4/0x8620 net/ipv4/nexthop.c:3282
 rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6958
 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:721 [inline]
 __sock_sendmsg net/socket.c:736 [inline]
 ____sys_sendmsg+0x972/0x9f0 net/socket.c:2585
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2639
 __sys_sendmsg net/socket.c:2671 [inline]
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2674
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888034639600
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 8 bytes to the right of
 allocated 200-byte region [ffff888034639600, ffff8880346396c8)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x34638
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88813fea8b40 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813fea8b40 dead000000000100 dead000000000122
head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 00fff00000000001 ffffea0000d18e01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 21082, tgid 21081 (syz.2.4011), ts 435397290413, free_ts 387404932835
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3296 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3485
 new_slab mm/slub.c:3543 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7178
 __pcs_replace_empty_main+0x2f9/0x5e0 mm/slub.c:-1
 alloc_from_pcs mm/slub.c:4720 [inline]
 slab_alloc_node mm/slub.c:4854 [inline]
 __do_kmalloc_node mm/slub.c:5262 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5275
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 hash_ipportnet6_resize+0xe84/0x1f00 net/netfilter/ipset/ip_set_hash_gen.h:725
 call_ad+0x463/0xb60 net/netfilter/ipset/ip_set_core.c:1757
 ip_set_ad+0x824/0x9d0 net/netfilter/ipset/ip_set_core.c:1841
 nfnetlink_rcv_msg+0xc00/0x12c0 net/netfilter/nfnetlink.c:300
 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
 nfnetlink_rcv+0x2c0/0x27b0 net/netfilter/nfnetlink.c:667
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:721 [inline]
 __sock_sendmsg net/socket.c:736 [inline]
 ____sys_sendmsg+0x972/0x9f0 net/socket.c:2585
page last free pid 23 tgid 23 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 __tlb_remove_table_free mm/mmu_gather.c:228 [inline]
 tlb_remove_table_rcu+0x85/0x100 mm/mmu_gather.c:291
 rcu_do_batch kernel/rcu/tree.c:2617 [inline]
 rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
 handle_softirqs+0x22a/0x870 kernel/softirq.c:622
 run_ksoftirqd+0x36/0x60 kernel/softirq.c:1063
 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888034639580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888034639600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888034639680: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
                                                 ^
 ffff888034639700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888034639780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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