syzbot

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BUG: KASAN: use-after-free in vlan_dev_get_iflink+0x70/0x80 net/8021q/vlan_dev.c:780
Read of size 4 at addr ffff888121678100 by task kworker/u4:1/9

CPU: 1 PID: 9 Comm: kworker/u4:1 Not tainted 5.10.236-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: netns cleanup_net
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack_lvl+0x1e2/0x24b lib/dump_stack.c:118
 print_address_description+0x81/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0x179/0x1c0 mm/kasan/report.c:452
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 vlan_dev_get_iflink+0x70/0x80 net/8021q/vlan_dev.c:780
 dev_get_iflink+0x6f/0xc0 net/core/dev.c:824
 default_operstate net/core/link_watch.c:41 [inline]
 rfc2863_policy+0x127/0x2b0 net/core/link_watch.c:53
 linkwatch_do_dev+0x3c/0x140 net/core/link_watch.c:160
 linkwatch_forget_dev+0x170/0x180 net/core/link_watch.c:238
 netdev_wait_allrefs net/core/dev.c:10214 [inline]
 netdev_run_todo+0x2ee/0xdc0 net/core/dev.c:10330
 rtnl_unlock+0xe/0x10 net/core/rtnetlink.c:112
 default_device_exit_batch+0x38f/0x3f0 net/core/dev.c:11287
 ops_exit_list net/core/net_namespace.c:190 [inline]
 cleanup_net+0x6e9/0xcb0 net/core/net_namespace.c:609
 process_one_work+0x6dc/0xbd0 kernel/workqueue.c:2301
 worker_thread+0xaea/0x1510 kernel/workqueue.c:2447
 kthread+0x34b/0x3d0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

Allocated by task 289:
 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+0xdb/0x110 mm/kasan/common.c:509
 __kasan_kmalloc+0x9/0x10 mm/kasan/common.c:518
 kasan_kmalloc include/linux/kasan.h:254 [inline]
 __kmalloc+0x1aa/0x330 mm/slub.c:4033
 __kmalloc_node include/linux/slab.h:418 [inline]
 kmalloc_node include/linux/slab.h:575 [inline]
 kvmalloc_node+0x82/0x130 mm/util.c:612
 kvmalloc include/linux/mm.h:822 [inline]
 kvzalloc include/linux/mm.h:830 [inline]
 alloc_netdev_mqs+0x8e/0xcd0 net/core/dev.c:10526
 rtnl_create_link+0x240/0x950 net/core/rtnetlink.c:3195
 __rtnl_newlink net/core/rtnetlink.c:3472 [inline]
 rtnl_newlink+0x1399/0x2000 net/core/rtnetlink.c:3530
 rtnetlink_rcv_msg+0x955/0xc50 net/core/rtnetlink.c:5610
 netlink_rcv_skb+0x1cf/0x410 net/netlink/af_netlink.c:2485
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5628
 netlink_unicast_kernel net/netlink/af_netlink.c:1307 [inline]
 netlink_unicast+0x8df/0xac0 net/netlink/af_netlink.c:1333
 netlink_sendmsg+0xa46/0xd00 net/netlink/af_netlink.c:1901
 sock_sendmsg_nosec net/socket.c:652 [inline]
 __sock_sendmsg net/socket.c:664 [inline]
 __sys_sendto+0x545/0x700 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 9:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x121/0x160 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:1595 [inline]
 slab_free_freelist_hook+0xc0/0x190 mm/slub.c:1621
 slab_free mm/slub.c:3203 [inline]
 kfree+0xc3/0x270 mm/slub.c:4191
 kvfree+0x35/0x40 mm/util.c:647
 netdev_freemem+0x3f/0x60 net/core/dev.c:10480
 netdev_release+0x7f/0xb0 net/core/net-sysfs.c:1886
 device_release+0x95/0x1c0 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+0x178/0x260 lib/kobject.c:761
 netdev_run_todo+0xc26/0xdc0 net/core/dev.c:10351
 rtnl_unlock+0xe/0x10 net/core/rtnetlink.c:112
 default_device_exit_batch+0x38f/0x3f0 net/core/dev.c:11287
 ops_exit_list net/core/net_namespace.c:190 [inline]
 cleanup_net+0x6e9/0xcb0 net/core/net_namespace.c:609
 process_one_work+0x6dc/0xbd0 kernel/workqueue.c:2301
 worker_thread+0xaea/0x1510 kernel/workqueue.c:2447
 kthread+0x34b/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 ffff888121678000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 256 bytes inside of
 4096-byte region [ffff888121678000, ffff888121679000)
The buggy address belongs to the page:
page:ffffea0004859e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x121678
head:ffffea0004859e00 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 289, ts 23049824441, 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+0x166/0x180 mm/page_alloc.c:2462
 get_page_from_freelist+0x2d8c/0x2f30 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x435/0xaf0 mm/page_alloc.c:5349
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1808 [inline]
 new_slab+0x80/0x400 mm/slub.c:1869
 new_slab_objects mm/slub.c:2627 [inline]
 ___slab_alloc+0x302/0x4b0 mm/slub.c:2791
 __slab_alloc+0x63/0xa0 mm/slub.c:2831
 slab_alloc_node mm/slub.c:2913 [inline]
 slab_alloc mm/slub.c:2955 [inline]
 __kmalloc_track_caller+0x1f8/0x320 mm/slub.c:4536
 kmemdup+0x24/0x50 mm/util.c:131
 __addrconf_sysctl_register+0xad/0x3e0 net/ipv6/addrconf.c:7031
 addrconf_sysctl_register+0x141/0x1a0 net/ipv6/addrconf.c:7096
 ipv6_add_dev+0xc11/0x10b0 net/ipv6/addrconf.c:448
 addrconf_notify+0x58e/0xe90 net/ipv6/addrconf.c:3567
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0x8c/0xf0 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+0x145/0x1b0 net/core/dev.c:2080
 register_netdevice+0x1066/0x13f0 net/core/dev.c:10086
 veth_newlink+0x835/0xb50 drivers/net/veth.c:1387
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888121678000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888121678080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888121678100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888121678180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888121678200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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