================================================================== BUG: KASAN: use-after-free in nexthop_flush_dev+0x20b/0x230 net/ipv4/nexthop.c:2381 Read of size 8 at addr ffff88801dcf6058 by task syz-executor.1/3615 CPU: 1 PID: 3615 Comm: syz-executor.1 Not tainted 5.18.0-syzkaller-04986-g90343f573252 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description.constprop.0.cold+0xeb/0x495 mm/kasan/report.c:313 print_report mm/kasan/report.c:429 [inline] kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491 nexthop_flush_dev+0x20b/0x230 net/ipv4/nexthop.c:2381 nh_netdev_event+0x2c6/0x370 net/ipv4/nexthop.c:3574 notifier_call_chain+0xb5/0x200 kernel/notifier.c:84 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1943 call_netdevice_notifiers_extack net/core/dev.c:1981 [inline] call_netdevice_notifiers net/core/dev.c:1995 [inline] netdev_wait_allrefs_any net/core/dev.c:10225 [inline] netdev_run_todo+0xb90/0x10b0 net/core/dev.c:10337 tun_detach drivers/net/tun.c:695 [inline] tun_chr_close+0xe0/0x180 drivers/net/tun.c:3444 __fput+0x277/0x9d0 fs/file_table.c:317 task_work_run+0xdd/0x1a0 kernel/task_work.c:177 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xaff/0x2a00 kernel/exit.c:795 do_group_exit+0xd2/0x2f0 kernel/exit.c:925 __do_sys_exit_group kernel/exit.c:936 [inline] __se_sys_exit_group kernel/exit.c:934 [inline] __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:934 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+0x46/0xb0 RIP: 0033:0x7f6023689109 Code: Unable to access opcode bytes at RIP 0x7f60236890df. RSP: 002b:00007ffe2a4c47d8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007ffe2a4c4980 RCX: 00007f6023689109 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000043 RBP: 0000000000000000 R08: 0000000000000025 R09: 00007ffe2a4c4980 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f60236e305e R13: 000000000000001c R14: 000000000000000c R15: 00007ffe2a4c49c0 Allocated by task 3615: 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:436 [inline] ____kasan_kmalloc mm/kasan/common.c:515 [inline] ____kasan_kmalloc mm/kasan/common.c:474 [inline] __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:524 kmalloc include/linux/slab.h:588 [inline] kzalloc include/linux/slab.h:721 [inline] nexthop_net_init+0x71/0x140 net/ipv4/nexthop.c:3753 ops_init+0xaf/0x470 net/core/net_namespace.c:134 setup_net+0x5d1/0xc50 net/core/net_namespace.c:325 copy_net_ns+0x318/0x760 net/core/net_namespace.c:471 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:226 ksys_unshare+0x445/0x920 kernel/fork.c:3137 __do_sys_unshare kernel/fork.c:3208 [inline] __se_sys_unshare kernel/fork.c:3206 [inline] __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3206 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+0x46/0xb0 Freed by task 52: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track+0x21/0x30 mm/kasan/common.c:45 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370 ____kasan_slab_free mm/kasan/common.c:366 [inline] ____kasan_slab_free+0x166/0x1a0 mm/kasan/common.c:328 kasan_slab_free include/linux/kasan.h:200 [inline] slab_free_hook mm/slub.c:1727 [inline] slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1753 slab_free mm/slub.c:3507 [inline] kfree+0xd6/0x4d0 mm/slub.c:4555 nexthop_net_exit_batch+0x245/0x2d0 net/ipv4/nexthop.c:3743 ops_exit_list+0x125/0x170 net/core/net_namespace.c:167 cleanup_net+0x4ea/0xb00 net/core/net_namespace.c:594 process_one_work+0x996/0x1610 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e9/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302 The buggy address belongs to the object at ffff88801dcf6000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 88 bytes inside of 2048-byte region [ffff88801dcf6000, ffff88801dcf6800) The buggy address belongs to the physical page: page:ffffea0000773c00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1dcf0 head:ffffea0000773c00 order:3 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888010c42000 raw: 0000000000000000 0000000000080008 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 3615, tgid 3615 (syz-executor.1), ts 53713379862, free_ts 49083077557 prep_new_page mm/page_alloc.c:2441 [inline] get_page_from_freelist+0xba2/0x3e00 mm/page_alloc.c:4182 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5408 alloc_pages+0x1aa/0x310 mm/mempolicy.c:2272 alloc_slab_page mm/slub.c:1797 [inline] allocate_slab+0x26c/0x3c0 mm/slub.c:1942 new_slab mm/slub.c:2002 [inline] ___slab_alloc+0x985/0xd90 mm/slub.c:3002 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3089 slab_alloc_node mm/slub.c:3180 [inline] slab_alloc mm/slub.c:3222 [inline] __kmalloc+0x318/0x350 mm/slub.c:4413 kmalloc include/linux/slab.h:593 [inline] sk_prot_alloc+0x110/0x290 net/core/sock.c:1975 sk_alloc+0x36/0x770 net/core/sock.c:2028 __netlink_create+0x63/0x2f0 net/netlink/af_netlink.c:647 __netlink_kernel_create+0x110/0x850 net/netlink/af_netlink.c:2045 netlink_kernel_create include/linux/netlink.h:62 [inline] rtnetlink_net_init+0xb8/0x140 net/core/rtnetlink.c:6165 ops_init+0xaf/0x470 net/core/net_namespace.c:134 setup_net+0x5d1/0xc50 net/core/net_namespace.c:325 copy_net_ns+0x318/0x760 net/core/net_namespace.c:471 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1356 [inline] free_pcp_prepare+0x549/0xd20 mm/page_alloc.c:1406 free_unref_page_prepare mm/page_alloc.c:3328 [inline] free_unref_page+0x19/0x6a0 mm/page_alloc.c:3423 __unfreeze_partials+0x17c/0x1a0 mm/slub.c:2521 qlink_free mm/kasan/quarantine.c:157 [inline] qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:176 kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:283 __kasan_slab_alloc+0xa2/0xc0 mm/kasan/common.c:446 kasan_slab_alloc include/linux/kasan.h:224 [inline] slab_post_alloc_hook mm/slab.h:750 [inline] slab_alloc_node mm/slub.c:3214 [inline] __kmalloc_node+0x23a/0x390 mm/slub.c:4461 kmalloc_node include/linux/slab.h:611 [inline] kvmalloc_node+0x3e/0x190 mm/util.c:612 kvmalloc include/linux/slab.h:738 [inline] seq_buf_alloc fs/seq_file.c:38 [inline] seq_read_iter+0x7f7/0x1280 fs/seq_file.c:210 kernfs_fop_read_iter+0x514/0x6f0 fs/kernfs/file.c:236 call_read_iter include/linux/fs.h:2035 [inline] new_sync_read+0x384/0x5f0 fs/read_write.c:401 vfs_read+0x492/0x5d0 fs/read_write.c:482 ksys_read+0x127/0x250 fs/read_write.c:620 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+0x46/0xb0 Memory state around the buggy address: ffff88801dcf5f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88801dcf5f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88801dcf6000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88801dcf6080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88801dcf6100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================