================================================================== BUG: KASAN: use-after-free in nexthop_flush_dev net/ipv4/nexthop.c:2382 [inline] BUG: KASAN: use-after-free in nh_netdev_event+0x13c/0x940 net/ipv4/nexthop.c:3575 Read of size 8 at addr ffff888024421058 by task syz-executor.3/6561 CPU: 1 PID: 6561 Comm: syz-executor.3 Not tainted 6.1.0-rc5-syzkaller-00015-g81e7cfa3a9eb #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106 print_address_description+0x74/0x340 mm/kasan/report.c:284 print_report+0x107/0x220 mm/kasan/report.c:395 kasan_report+0x139/0x170 mm/kasan/report.c:495 nexthop_flush_dev net/ipv4/nexthop.c:2382 [inline] nh_netdev_event+0x13c/0x940 net/ipv4/nexthop.c:3575 notifier_call_chain kernel/notifier.c:87 [inline] raw_notifier_call_chain+0xe7/0x170 kernel/notifier.c:455 call_netdevice_notifiers_info net/core/dev.c:1945 [inline] call_netdevice_notifiers_extack net/core/dev.c:1983 [inline] call_netdevice_notifiers net/core/dev.c:1997 [inline] netdev_wait_allrefs_any net/core/dev.c:10237 [inline] netdev_run_todo+0x8fb/0x1090 net/core/dev.c:10351 tun_detach drivers/net/tun.c:704 [inline] tun_chr_close+0x11f/0x130 drivers/net/tun.c:3467 __fput+0x3ba/0x880 fs/file_table.c:320 task_work_run+0x243/0x300 kernel/task_work.c:179 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0x664/0x2070 kernel/exit.c:820 do_group_exit+0x1fd/0x2b0 kernel/exit.c:950 get_signal+0x1743/0x1810 kernel/signal.c:2858 arch_do_signal_or_restart+0x8d/0x750 arch/x86/kernel/signal.c:869 exit_to_user_mode_loop+0x74/0x160 kernel/entry/common.c:168 exit_to_user_mode_prepare+0xad/0x110 kernel/entry/common.c:203 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] syscall_exit_to_user_mode+0x2e/0x60 kernel/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f0abeeb0361 Code: Unable to access opcode bytes at 0x7f0abeeb0337. RSP: 002b:00007f0abfb700b0 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6 RAX: fffffffffffffdfc RBX: 00007f0abefabf80 RCX: 00007f0abeeb0361 RDX: 00007f0abfb700f0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007f0abeee6ae9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 00007ffd9327dfef R14: 00007f0abfb70300 R15: 0000000000022000 Allocated by task 3667: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4c/0x70 mm/kasan/common.c:52 ____kasan_kmalloc mm/kasan/common.c:371 [inline] __kasan_kmalloc+0x97/0xb0 mm/kasan/common.c:380 kmalloc include/linux/slab.h:553 [inline] kzalloc include/linux/slab.h:689 [inline] nexthop_net_init+0x71/0x100 net/ipv4/nexthop.c:3754 ops_init+0x353/0x5d0 net/core/net_namespace.c:135 setup_net+0x4bb/0xc10 net/core/net_namespace.c:332 copy_net_ns+0x359/0x5b0 net/core/net_namespace.c:478 create_new_namespaces+0x4db/0x8e0 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0x11e/0x180 kernel/nsproxy.c:226 ksys_unshare+0x57f/0xb30 kernel/fork.c:3188 __do_sys_unshare kernel/fork.c:3259 [inline] __se_sys_unshare kernel/fork.c:3257 [inline] __x64_sys_unshare+0x34/0x40 kernel/fork.c:3257 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Freed by task 3782: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4c/0x70 mm/kasan/common.c:52 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:511 ____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236 kasan_slab_free include/linux/kasan.h:177 [inline] slab_free_hook mm/slub.c:1724 [inline] slab_free_freelist_hook+0x12e/0x1a0 mm/slub.c:1750 slab_free mm/slub.c:3661 [inline] __kmem_cache_free+0x71/0x110 mm/slub.c:3674 nexthop_net_exit_batch+0x24b/0x2a0 net/ipv4/nexthop.c:3744 ops_exit_list net/core/net_namespace.c:174 [inline] cleanup_net+0x80c/0xc50 net/core/net_namespace.c:601 process_one_work+0x81c/0xd10 kernel/workqueue.c:2289 worker_thread+0xb14/0x1330 kernel/workqueue.c:2436 kthread+0x266/0x300 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 The buggy address belongs to the object at ffff888024421000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 88 bytes inside of 2048-byte region [ffff888024421000, ffff888024421800) The buggy address belongs to the physical page: page:ffffea0000910800 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888024427000 pfn:0x24420 head:ffffea0000910800 order:3 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 ffffea00008b7208 ffffea000086f808 ffff888012842000 raw: ffff888024427000 0000000000080005 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 3667, tgid 3667 (syz-executor.3), ts 161799247237, free_ts 161795328162 prep_new_page mm/page_alloc.c:2539 [inline] get_page_from_freelist+0x72b/0x7a0 mm/page_alloc.c:4288 __alloc_pages+0x259/0x560 mm/page_alloc.c:5555 alloc_slab_page+0x70/0xf0 mm/slub.c:1794 allocate_slab+0x5e/0x4b0 mm/slub.c:1939 new_slab mm/slub.c:1992 [inline] ___slab_alloc+0x7f4/0xeb0 mm/slub.c:3180 __slab_alloc mm/slub.c:3279 [inline] slab_alloc_node mm/slub.c:3364 [inline] __kmem_cache_alloc_node+0x252/0x310 mm/slub.c:3437 kmalloc_trace+0x26/0x60 mm/slab_common.c:1045 kmalloc include/linux/slab.h:553 [inline] kmalloc_array include/linux/slab.h:604 [inline] netdev_create_hash net/core/dev.c:11153 [inline] netdev_init+0x108/0x1f0 net/core/dev.c:11173 ops_init+0x353/0x5d0 net/core/net_namespace.c:135 setup_net+0x4bb/0xc10 net/core/net_namespace.c:332 copy_net_ns+0x359/0x5b0 net/core/net_namespace.c:478 create_new_namespaces+0x4db/0x8e0 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0x11e/0x180 kernel/nsproxy.c:226 ksys_unshare+0x57f/0xb30 kernel/fork.c:3188 __do_sys_unshare kernel/fork.c:3259 [inline] __se_sys_unshare kernel/fork.c:3257 [inline] __x64_sys_unshare+0x34/0x40 kernel/fork.c:3257 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1459 [inline] free_pcp_prepare+0x80c/0x8f0 mm/page_alloc.c:1509 free_unref_page_prepare mm/page_alloc.c:3387 [inline] free_unref_page+0x7d/0x630 mm/page_alloc.c:3483 free_large_kmalloc+0x10b/0x1a0 mm/slab_common.c:932 skb_free_head net/core/skbuff.c:760 [inline] skb_release_data+0x536/0x6d0 net/core/skbuff.c:789 skb_release_all net/core/skbuff.c:854 [inline] __kfree_skb+0x56/0x1d0 net/core/skbuff.c:868 netlink_recvmsg+0x5c1/0x10f0 net/netlink/af_netlink.c:1998 ____sys_recvmsg+0x285/0x530 ___sys_recvmsg net/socket.c:2743 [inline] __sys_recvmsg+0x294/0x390 net/socket.c:2773 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Memory state around the buggy address: ffff888024420f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888024420f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888024421000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888024421080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888024421100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================