================================================================== BUG: KASAN: use-after-free in vlan_dev_get_iflink+0x6d/0x70 net/8021q/vlan_dev.c:757 Read of size 4 at addr ffff8881335d2100 by task kworker/u4:2/48 CPU: 1 PID: 48 Comm: kworker/u4:2 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Workqueue: events_unbound linkwatch_event Call Trace: __dump_stack+0x21/0x24 lib/dump_stack.c:77 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:435 [inline] kasan_report+0xe2/0x130 mm/kasan/report.c:452 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308 vlan_dev_get_iflink+0x6d/0x70 net/8021q/vlan_dev.c:757 dev_get_iflink+0x70/0xc0 net/core/dev.c:824 default_operstate net/core/link_watch.c:41 [inline] rfc2863_policy+0x124/0x2b0 net/core/link_watch.c:53 linkwatch_do_dev+0x3b/0x140 net/core/link_watch.c:160 __linkwatch_run_queue+0x4b1/0x7c0 net/core/link_watch.c:213 linkwatch_event+0x4c/0x60 net/core/link_watch.c:252 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301 worker_thread+0xa6a/0x13c0 kernel/workqueue.c:2447 kthread+0x346/0x3d0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 Allocated by task 837: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:430 [inline] ____kasan_kmalloc mm/kasan/common.c:509 [inline] __kasan_kmalloc+0xda/0x110 mm/kasan/common.c:518 kasan_kmalloc include/linux/kasan.h:254 [inline] __kmalloc+0x1a4/0x330 mm/slub.c:4038 __kmalloc_node include/linux/slab.h:421 [inline] kmalloc_node include/linux/slab.h:578 [inline] kvmalloc_node+0x88/0x130 mm/util.c:612 kvmalloc include/linux/mm.h:833 [inline] kvzalloc include/linux/mm.h:841 [inline] alloc_netdev_mqs+0x88/0xc80 net/core/dev.c:10540 rtnl_create_link+0x242/0x930 net/core/rtnetlink.c:3198 __rtnl_newlink net/core/rtnetlink.c:3475 [inline] rtnl_newlink+0x11bc/0x18f0 net/core/rtnetlink.c:3533 rtnetlink_rcv_msg+0xa31/0xcc0 net/core/rtnetlink.c:5613 netlink_rcv_skb+0x1f5/0x440 net/netlink/af_netlink.c:2503 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5631 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] netlink_unicast+0x876/0xa40 net/netlink/af_netlink.c:1340 netlink_sendmsg+0x89c/0xb50 net/netlink/af_netlink.c:1914 sock_sendmsg_nosec net/socket.c:652 [inline] __sock_sendmsg net/socket.c:664 [inline] __sys_sendto+0x467/0x620 net/socket.c:2006 __do_sys_sendto net/socket.c:2018 [inline] __se_sys_sendto net/socket.c:2014 [inline] __x64_sys_sendto+0xe5/0x100 net/socket.c:2014 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb Freed by task 7: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4a/0x70 mm/kasan/common.c:45 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370 kasan_slab_free include/linux/kasan.h:220 [inline] slab_free_hook mm/slub.c:1600 [inline] slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626 slab_free mm/slub.c:3208 [inline] kfree+0xc0/0x270 mm/slub.c:4196 kvfree+0x35/0x40 mm/util.c:647 netdev_freemem+0x3f/0x60 net/core/dev.c:10494 netdev_release+0x7f/0xb0 net/core/net-sysfs.c:1886 device_release+0x96/0x1c0 drivers/base/core.c:-1 kobject_cleanup lib/kobject.c:713 [inline] kobject_release lib/kobject.c:744 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x18a/0x270 lib/kobject.c:761 netdev_run_todo+0xbbc/0xd50 net/core/dev.c:10365 rtnl_unlock+0xe/0x10 net/core/rtnetlink.c:112 default_device_exit_batch+0x363/0x3c0 net/core/dev.c:11301 ops_exit_list net/core/net_namespace.c:190 [inline] cleanup_net+0x603/0xb80 net/core/net_namespace.c:609 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301 worker_thread+0xa6a/0x13c0 kernel/workqueue.c:2447 kthread+0x346/0x3d0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 The buggy address belongs to the object at ffff8881335d2000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 256 bytes inside of 4096-byte region [ffff8881335d2000, ffff8881335d3000) The buggy address belongs to the page: page:ffffea0004cd7400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1335d0 head:ffffea0004cd7400 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head) raw: 4000000000010200 dead000000000100 dead000000000122 ffff888100042c00 raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 837, ts 43589268454, free_ts 0 set_page_owner include/linux/page_owner.h:35 [inline] post_alloc_hook mm/page_alloc.c:2456 [inline] prep_new_page+0x179/0x180 mm/page_alloc.c:2462 get_page_from_freelist+0x223b/0x23d0 mm/page_alloc.c:4254 __alloc_pages_nodemask+0x290/0x620 mm/page_alloc.c:5384 alloc_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1813 [inline] new_slab+0x84/0x3f0 mm/slub.c:1874 new_slab_objects mm/slub.c:2632 [inline] ___slab_alloc+0x2a6/0x450 mm/slub.c:2796 __slab_alloc+0x63/0xa0 mm/slub.c:2836 slab_alloc_node mm/slub.c:2918 [inline] slab_alloc mm/slub.c:2960 [inline] __kmalloc_track_caller+0x1ec/0x320 mm/slub.c:4541 kmemdup+0x26/0x60 mm/util.c:131 __addrconf_sysctl_register+0xb6/0x3e0 net/ipv6/addrconf.c:7046 addrconf_sysctl_register+0x147/0x1a0 net/ipv6/addrconf.c:7111 ipv6_add_dev+0xbaf/0x10a0 net/ipv6/addrconf.c:450 addrconf_notify+0x582/0xe90 net/ipv6/addrconf.c:3571 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0x90/0x100 kernel/notifier.c:410 call_netdevice_notifiers_info net/core/dev.c:2054 [inline] call_netdevice_notifiers_extack net/core/dev.c:2066 [inline] call_netdevice_notifiers+0x119/0x190 net/core/dev.c:2080 register_netdevice+0x1056/0x13e0 net/core/dev.c:10100 veth_newlink+0x853/0xb60 drivers/net/veth.c:1387 page_owner free stack trace missing Memory state around the buggy address: ffff8881335d2000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881335d2080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881335d2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881335d2180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881335d2200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================