syzbot

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BUG: KASAN: slab-use-after-free in macvlan_forward_source+0x5d8/0x700 drivers/net/macvlan.c:442
Read of size 2 at addr ffff888028d26dfc by task syz.4.2652/15566

CPU: 1 UID: 0 PID: 15566 Comm: syz.4.2652 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026
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
 macvlan_forward_source+0x5d8/0x700 drivers/net/macvlan.c:442
 macvlan_handle_frame+0x2e2/0x12e0 drivers/net/macvlan.c:477
 __netif_receive_skb_core+0x98f/0x30a0 net/core/dev.c:6039
 __netif_receive_skb_one_core net/core/dev.c:6150 [inline]
 __netif_receive_skb net/core/dev.c:6265 [inline]
 netif_receive_skb_internal net/core/dev.c:6351 [inline]
 netif_receive_skb+0x1fe/0xbb0 net/core/dev.c:6410
 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:593 [inline]
 vfs_write+0x61d/0xb90 fs/read_write.c:686
 ksys_write+0x150/0x270 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fba5df5b78e
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:00007fba5ee4afb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fba5ee4b6c0 RCX: 00007fba5df5b78e
RDX: 000000000000006e RSI: 0000200000000080 RDI: 00000000000000c8
RBP: 00007fba5e008c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fba5e216128 R14: 00007fba5e216090 R15: 00007fff4c1c8888
 </TASK>

Allocated by task 15383:
 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]
 __do_kmalloc_node mm/slub.c:5657 [inline]
 __kvmalloc_node_noprof+0x59a/0x8d0 mm/slub.c:7140
 seq_buf_alloc fs/seq_file.c:38 [inline]
 traverse+0xde/0x580 fs/seq_file.c:102
 seq_read_iter+0xd08/0xe10 fs/seq_file.c:195
 do_iter_readv_writev+0x619/0x8c0 fs/read_write.c:-1
 vfs_readv+0x288/0x840 fs/read_write.c:1018
 do_preadv fs/read_write.c:1132 [inline]
 __do_sys_preadv fs/read_write.c:1179 [inline]
 __se_sys_preadv fs/read_write.c:1174 [inline]
 __x64_sys_preadv+0x19f/0x2a0 fs/read_write.c:1174
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 15382:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2540 [inline]
 slab_free mm/slub.c:6674 [inline]
 kfree+0x1be/0x650 mm/slub.c:6882
 seq_release+0x54/0x70 fs/seq_file.c:355
 kernfs_fop_release+0x30f/0x460 fs/kernfs/file.c:784
 __fput+0x44f/0xa70 fs/file_table.c:468
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
 exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x2b7/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888028d26000
 which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 3580 bytes inside of
 freed 4096-byte region [ffff888028d26000, ffff888028d27000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x28d20
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff8880311f7e81
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88813fe30500 ffffea0000a99c00 0000000000000002
raw: 0000000000000000 0000000000040004 00000000f5000000 ffff8880311f7e81
head: 00fff00000000040 ffff88813fe30500 ffffea0000a99c00 0000000000000002
head: 0000000000000000 0000000000040004 00000000f5000000 ffff8880311f7e81
head: 00fff00000000003 ffffea0000a34801 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 14073, tgid 14071 (syz.1.2259), ts 344621616476, free_ts 344619072302
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x228/0x280 mm/page_alloc.c:1884
 prep_new_page mm/page_alloc.c:1892 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3945
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5240
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab+0x86/0x3a0 mm/slub.c:3248
 new_slab mm/slub.c:3302 [inline]
 ___slab_alloc+0xd82/0x1760 mm/slub.c:4656
 __slab_alloc+0x65/0x100 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5251 [inline]
 __kmalloc_cache_noprof+0x40d/0x6e0 mm/slub.c:5775
 kmalloc_noprof include/linux/slab.h:957 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 snmp6_alloc_dev net/ipv6/addrconf.c:362 [inline]
 ipv6_add_dev+0x6aa/0x13a0 net/ipv6/addrconf.c:413
 addrconf_notify+0x771/0x1050 net/ipv6/addrconf.c:3650
 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2281 [inline]
 call_netdevice_notifiers net/core/dev.c:2295 [inline]
 register_netdevice+0x171a/0x1cd0 net/core/dev.c:11444
 register_netdev+0x40/0x60 net/core/dev.c:11522
 vti6_init_net+0x238/0x370 net/ipv6/ip6_vti.c:1158
 ops_init+0x35c/0x5c0 net/core/net_namespace.c:137
 setup_net+0x118/0x340 net/core/net_namespace.c:446
page last free pid 14124 tgid 14121 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xbf8/0xd70 mm/page_alloc.c:2973
 bpf_check+0x168af/0x1c4c0 kernel/bpf/verifier.c:25401
 bpf_prog_load+0x1484/0x1ae0 kernel/bpf/syscall.c:3088
 __sys_bpf+0x570/0x920 kernel/bpf/syscall.c:6164
 __do_sys_bpf kernel/bpf/syscall.c:6274 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6272 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6272
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888028d26c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888028d26d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888028d26d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff888028d26e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888028d26e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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