================================================================== BUG: KASAN: use-after-free in nexthop_flush_dev+0x20b/0x230 net/ipv4/nexthop.c:2382 Read of size 8 at addr ffff888025be3058 by task syz-executor.1/22742 CPU: 0 PID: 22742 Comm: syz-executor.1 Not tainted 6.0.0-rc5-syzkaller-00025-g3245cb65fd91 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:317 [inline] print_report.cold+0x2ba/0x6e9 mm/kasan/report.c:433 kasan_report+0xb1/0x1e0 mm/kasan/report.c:495 nexthop_flush_dev+0x20b/0x230 net/ipv4/nexthop.c:2382 nh_netdev_event+0x2c6/0x370 net/ipv4/nexthop.c:3575 notifier_call_chain+0xb5/0x200 kernel/notifier.c:87 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1945 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:10250 [inline] netdev_run_todo+0xbc2/0x1100 net/core/dev.c:10364 tun_detach drivers/net/tun.c:704 [inline] tun_chr_close+0xe0/0x180 drivers/net/tun.c:3455 __fput+0x277/0x9d0 fs/file_table.c:320 task_work_run+0xdd/0x1a0 kernel/task_work.c:177 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xad5/0x29b0 kernel/exit.c:795 do_group_exit+0xd2/0x2f0 kernel/exit.c:925 get_signal+0x238c/0x2610 kernel/signal.c:2857 arch_do_signal_or_restart+0x82/0x2300 arch/x86/kernel/signal.c:869 exit_to_user_mode_loop kernel/entry/common.c:166 [inline] exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline] syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:294 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f4dabeac96f Code: Unable to access opcode bytes at RIP 0x7f4dabeac945. RSP: 002b:00007f4dacfab0a8 EFLAGS: 00000292 ORIG_RAX: 00000000000000ca RAX: ffffffffffffffea RBX: 00007f4dabf9c050 RCX: 00007f4dabeac96f RDX: 00007f4dacfab0f0 RSI: 0000000000000080 RDI: d43d718426609a02 RBP: 00007f4dabee4367 R08: 000000008e374485 R09: 0000000020000700 R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000 R13: 00007ffe56adbaaf R14: 00007f4dacfab300 R15: 0000000000022000 Allocated by task 3889: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:437 [inline] ____kasan_kmalloc mm/kasan/common.c:516 [inline] ____kasan_kmalloc mm/kasan/common.c:475 [inline] __kasan_kmalloc+0xa6/0xd0 mm/kasan/common.c:525 kasan_kmalloc include/linux/kasan.h:234 [inline] kmem_cache_alloc_trace+0x25a/0x460 mm/slab.c:3559 kmalloc include/linux/slab.h:600 [inline] kzalloc include/linux/slab.h:733 [inline] nexthop_net_init+0x71/0x140 net/ipv4/nexthop.c:3754 ops_init+0xaf/0x470 net/core/net_namespace.c:135 setup_net+0x5d1/0xc50 net/core/net_namespace.c:326 copy_net_ns+0x318/0x760 net/core/net_namespace.c:472 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:227 ksys_unshare+0x445/0x920 kernel/fork.c:3184 __do_sys_unshare kernel/fork.c:3255 [inline] __se_sys_unshare kernel/fork.c:3253 [inline] __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3253 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd The buggy address belongs to the object at ffff888025be3000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 88 bytes inside of 2048-byte region [ffff888025be3000, ffff888025be3800) The buggy address belongs to the physical page: page:ffffea000096f8c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x25be3 flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 ffffea0000531988 ffffea0000756c08 ffff888011840800 raw: 0000000000000000 ffff888025be3000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2c2220(__GFP_HIGH|__GFP_ATOMIC|__GFP_NOWARN|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_THISNODE), pid 3694, tgid 3694 (syz-executor.0), ts 72297042280, free_ts 68496562181 prep_new_page mm/page_alloc.c:2532 [inline] get_page_from_freelist+0x109b/0x2ce0 mm/page_alloc.c:4283 __alloc_pages_slowpath.constprop.0+0x2d7/0x2240 mm/page_alloc.c:5058 __alloc_pages+0x43d/0x510 mm/page_alloc.c:5528 __alloc_pages_node include/linux/gfp.h:243 [inline] kmem_getpages mm/slab.c:1363 [inline] cache_grow_begin+0x75/0x360 mm/slab.c:2569 cache_alloc_refill+0x27f/0x380 mm/slab.c:2942 ____cache_alloc mm/slab.c:3018 [inline] ____cache_alloc mm/slab.c:3001 [inline] slab_alloc_node mm/slab.c:3220 [inline] kmem_cache_alloc_node_trace+0x50a/0x570 mm/slab.c:3601 __do_kmalloc_node mm/slab.c:3623 [inline] __kmalloc_node_track_caller+0x38/0x60 mm/slab.c:3638 kmalloc_reserve net/core/skbuff.c:362 [inline] __alloc_skb+0xd9/0x2f0 net/core/skbuff.c:434 alloc_skb include/linux/skbuff.h:1257 [inline] nlmsg_new include/net/netlink.h:953 [inline] rtmsg_ifinfo_build_skb+0x72/0x1a0 net/core/rtnetlink.c:3904 rtmsg_ifinfo_event net/core/rtnetlink.c:3940 [inline] rtmsg_ifinfo_event net/core/rtnetlink.c:3931 [inline] rtmsg_ifinfo+0x83/0x120 net/core/rtnetlink.c:3949 __dev_notify_flags+0x226/0x2b0 net/core/dev.c:8590 rtnl_configure_link+0x16b/0x240 net/core/rtnetlink.c:3199 rtnl_newlink_create net/core/rtnetlink.c:3371 [inline] __rtnl_newlink+0x10b8/0x17e0 net/core/rtnetlink.c:3580 rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3593 rtnetlink_rcv_msg+0x43a/0xca0 net/core/rtnetlink.c:6090 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2501 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1449 [inline] free_pcp_prepare+0x5e4/0xd20 mm/page_alloc.c:1499 free_unref_page_prepare mm/page_alloc.c:3380 [inline] free_unref_page+0x19/0x4d0 mm/page_alloc.c:3476 __folio_put_small mm/swap.c:105 [inline] __folio_put+0xc1/0x130 mm/swap.c:128 folio_put include/linux/mm.h:1125 [inline] put_page include/linux/mm.h:1177 [inline] anon_pipe_buf_release+0x3f7/0x4b0 fs/pipe.c:138 pipe_buf_release include/linux/pipe_fs_i.h:183 [inline] pipe_read+0x610/0x1100 fs/pipe.c:324 call_read_iter include/linux/fs.h:2181 [inline] new_sync_read fs/read_write.c:389 [inline] vfs_read+0x7f6/0x930 fs/read_write.c:470 ksys_read+0x1e8/0x250 fs/read_write.c:607 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Memory state around the buggy address: ffff888025be2f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888025be2f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888025be3000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888025be3080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888025be3100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================