syzbot

==================================================================
BUG: KASAN: slab-use-after-free in macvlan_forward_source+0x5d8/0x700 drivers/net/macvlan.c:442
Read of size 2 at addr ffff888032d5cdfc by task syz.0.2155/13920

CPU: 1 UID: 0 PID: 13920 Comm: syz.0.2155 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 macvlan_forward_source+0x5d8/0x700 drivers/net/macvlan.c:442
 macvlan_handle_frame+0x1ba/0x12e0 drivers/net/macvlan.c:501
 __netif_receive_skb_core+0x95f/0x2f90 net/core/dev.c:6039
 __netif_receive_skb_one_core net/core/dev.c:6150 [inline]
 __netif_receive_skb+0x72/0x380 net/core/dev.c:6265
 netif_receive_skb_internal net/core/dev.c:6351 [inline]
 netif_receive_skb+0x1bb/0x750 net/core/dev.c:6410
 tun_rx_batched+0x1b9/0x730 drivers/net/tun.c:1485
 tun_get_user+0x2aa3/0x3dc0 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+0x5c9/0xb30 fs/read_write.c:686
 ksys_write+0x145/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5ecb18e1ff
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:00007f5ecc10e000 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f5ecb3e5fa0 RCX: 00007f5ecb18e1ff
RDX: 000000000000002f RSI: 00002000000002c0 RDI: 00000000000000c8
RBP: 00007f5ecb213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000002f R11: 0000000000000293 R12: 0000000000000000
R13: 00007f5ecb3e6038 R14: 00007f5ecb3e5fa0 R15: 00007ffff3e32a08
 </TASK>

Allocated by task 13843:
 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+0x5d5/0x920 mm/slub.c:7136
 alloc_netdev_mqs+0xa6/0x11b0 net/core/dev.c:12012
 rtnl_create_link+0x31f/0xcf0 net/core/rtnetlink.c:3648
 rtnl_newlink_create+0x25c/0xb00 net/core/rtnetlink.c:3830
 __rtnl_newlink net/core/rtnetlink.c:3957 [inline]
 rtnl_newlink+0x16e7/0x1c90 net/core/rtnetlink.c:4072
 rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6958
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:742
 ____sys_sendmsg+0x505/0x820 net/socket.c:2592
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2646
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2683 [inline]
 __se_sys_sendmsg net/socket.c:2681 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2681
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 13843:
 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:6670 [inline]
 kfree+0x1c0/0x660 mm/slub.c:6878
 rtnl_newlink_create+0x373/0xb00 net/core/rtnetlink.c:3844
 __rtnl_newlink net/core/rtnetlink.c:3957 [inline]
 rtnl_newlink+0x16e7/0x1c90 net/core/rtnetlink.c:4072
 rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6958
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:742
 ____sys_sendmsg+0x505/0x820 net/socket.c:2592
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2646
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2683 [inline]
 __se_sys_sendmsg net/socket.c:2681 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2681
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888032d5c000
 which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 3580 bytes inside of
 freed 4096-byte region [ffff888032d5c000, ffff888032d5d000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x32d58
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff88802b7e0181
ksm flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88813ffb0500 ffffea0000d43000 dead000000000003
raw: 0000000000000000 0000000000040004 00000000f5000000 ffff88802b7e0181
head: 00fff00000000040 ffff88813ffb0500 ffffea0000d43000 dead000000000003
head: 0000000000000000 0000000000040004 00000000f5000000 ffff88802b7e0181
head: 00fff00000000003 ffffea0000cb5601 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 5838, tgid 5838 (syz-executor), ts 90135261635, free_ts 89922679144
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x234/0x290 mm/page_alloc.c:1857
 prep_new_page mm/page_alloc.c:1865 [inline]
 get_page_from_freelist+0x24e0/0x2580 mm/page_alloc.c:3915
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5210
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab+0x86/0x3b0 mm/slub.c:3248
 new_slab mm/slub.c:3302 [inline]
 ___slab_alloc+0xe53/0x1820 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]
 __do_kmalloc_node mm/slub.c:5656 [inline]
 __kmalloc_noprof+0x47d/0x800 mm/slub.c:5669
 kmalloc_noprof include/linux/slab.h:961 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 __register_sysctl_table+0x72/0x1340 fs/proc/proc_sysctl.c:1379
 __addrconf_sysctl_register+0x328/0x4c0 net/ipv6/addrconf.c:7323
 addrconf_sysctl_register+0x168/0x1c0 net/ipv6/addrconf.c:7371
 ipv6_add_dev+0xd26/0x13a0 net/ipv6/addrconf.c:460
 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+0x15c6/0x1a70 net/core/dev.c:11444
 xfrmi_create net/xfrm/xfrm_interface_core.c:252 [inline]
 xfrmi_newlink+0x49b/0x7b0 net/xfrm/xfrm_interface_core.c:855
page last free pid 5189 tgid 5189 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1406 [inline]
 __free_frozen_pages+0xbc8/0xd30 mm/page_alloc.c:2943
 discard_slab mm/slub.c:3346 [inline]
 __put_partials+0x146/0x170 mm/slub.c:3886
 __slab_free+0x294/0x320 mm/slub.c:5952
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 __kmalloc_cache_noprof+0x37c/0x700 mm/slub.c:5771
 kmalloc_noprof include/linux/slab.h:957 [inline]
 syslog_print+0xd2/0x590 kernel/printk/printk.c:1583
 do_syslog+0x544/0x760 kernel/printk/printk.c:1761
 __do_sys_syslog kernel/printk/printk.c:1853 [inline]
 __se_sys_syslog kernel/printk/printk.c:1851 [inline]
 __x64_sys_syslog+0x7c/0x90 kernel/printk/printk.c:1851
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888032d5cc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888032d5cd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888032d5cd80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff888032d5ce00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888032d5ce80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================