audit: type=1400 audit(1560767694.018:9): avc: denied { dac_override } for pid=2121 comm="syz-executor.0" capability=1 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 ================================================================== BUG: KASAN: use-after-free in pneigh_get_next.isra.4+0x273/0x2b0 net/core/neighbour.c:2652 Read of size 8 at addr ffff8801c61b1120 by task syz-executor.0/2402 CPU: 1 PID: 2402 Comm: syz-executor.0 Not tainted 4.9.141+ #1 ffff8801c5c77250 ffffffff81b42e79 ffffea0007186c40 ffff8801c61b1120 0000000000000000 ffff8801c61b1120 ffff8801c61b1120 ffff8801c5c77288 ffffffff815009b8 ffff8801c61b1120 0000000000000008 0000000000000000 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] print_address_description+0x6c/0x234 mm/kasan/report.c:256 [] kasan_report_error mm/kasan/report.c:355 [inline] [] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412 [] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 [] pneigh_get_next.isra.4+0x273/0x2b0 net/core/neighbour.c:2652 [] neigh_seq_next+0xb1/0x1e0 net/core/neighbour.c:2734 [] seq_read+0xa0b/0x12d0 fs/seq_file.c:270 [] proc_reg_read+0xfd/0x180 fs/proc/inode.c:203 [] do_loop_readv_writev.part.1+0xd5/0x280 fs/read_write.c:718 [] do_loop_readv_writev fs/read_write.c:707 [inline] [] do_readv_writev+0x56e/0x7b0 fs/read_write.c:873 [] vfs_readv+0x84/0xc0 fs/read_write.c:897 [] kernel_readv fs/splice.c:363 [inline] [] default_file_splice_read+0x451/0x7f0 fs/splice.c:435 [] do_splice_to+0x10c/0x170 fs/splice.c:899 [] splice_direct_to_actor+0x23f/0x7e0 fs/splice.c:971 [] do_splice_direct+0x1a3/0x270 fs/splice.c:1080 [] do_sendfile+0x4f0/0xc30 fs/read_write.c:1393 [] SYSC_sendfile64 fs/read_write.c:1454 [inline] [] SyS_sendfile64+0x144/0x160 fs/read_write.c:1440 [] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285 [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Allocated by task 2404: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 save_stack mm/kasan/kasan.c:505 [inline] set_track mm/kasan/kasan.c:517 [inline] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:609 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:594 __kmalloc+0x12f/0x310 mm/slub.c:3741 kmalloc include/linux/slab.h:495 [inline] pneigh_lookup+0x17d/0x3f0 net/core/neighbour.c:594 arp_req_set_public net/ipv4/arp.c:992 [inline] arp_req_set+0x443/0x570 net/ipv4/arp.c:1008 arp_ioctl+0x32a/0x670 net/ipv4/arp.c:1203 inet_ioctl+0x90/0x1d0 net/ipv4/af_inet.c:895 sock_do_ioctl+0x6a/0xb0 net/socket.c:905 sock_ioctl+0x32d/0x3c0 net/socket.c:991 vfs_ioctl fs/ioctl.c:43 [inline] file_ioctl fs/ioctl.c:493 [inline] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677 SYSC_ioctl fs/ioctl.c:694 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285 entry_SYSCALL_64_after_swapgs+0x5d/0xdb Freed by task 2401: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 save_stack mm/kasan/kasan.c:505 [inline] set_track mm/kasan/kasan.c:517 [inline] kasan_slab_free+0xac/0x190 mm/kasan/kasan.c:582 slab_free_hook mm/slub.c:1355 [inline] slab_free_freelist_hook mm/slub.c:1377 [inline] slab_free mm/slub.c:2958 [inline] kfree+0xfb/0x310 mm/slub.c:3878 pneigh_ifdown_and_unlock net/core/neighbour.c:674 [inline] neigh_ifdown+0x1da/0x2a0 net/core/neighbour.c:258 arp_ifdown+0x1c/0x20 net/ipv4/arp.c:1249 inetdev_destroy net/ipv4/devinet.c:306 [inline] inetdev_event+0x6f2/0x10b0 net/ipv4/devinet.c:1480 notifier_call_chain+0xb4/0x1d0 kernel/notifier.c:93 __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401 call_netdevice_notifiers_info+0x55/0x70 net/core/dev.c:1647 call_netdevice_notifiers net/core/dev.c:1663 [inline] rollback_registered_many+0x6e5/0xb50 net/core/dev.c:6860 rollback_registered+0xee/0x1b0 net/core/dev.c:6901 unregister_netdevice_queue+0x1aa/0x230 net/core/dev.c:7888 unregister_netdevice include/linux/netdevice.h:2465 [inline] __tun_detach+0x821/0xa00 drivers/net/tun.c:575 tun_detach drivers/net/tun.c:585 [inline] tun_chr_close+0x44/0x60 drivers/net/tun.c:2392 __fput+0x263/0x700 fs/file_table.c:208 ____fput+0x15/0x20 fs/file_table.c:244 task_work_run+0x10c/0x180 kernel/task_work.c:116 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x129/0x150 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] syscall_return_slowpath arch/x86/entry/common.c:263 [inline] do_syscall_64+0x3e2/0x550 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_swapgs+0x5d/0xdb The buggy address belongs to the object at ffff8801c61b1120 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 0 bytes inside of 64-byte region [ffff8801c61b1120, ffff8801c61b1160) The buggy address belongs to the page: page:ffffea0007186c40 count:1 mapcount:0 mapping: (null) index:0x0 flags: 0x4000000000000080(slab) page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801c61b1000: fb fb fb fb fb fb fb fb fc fc fc fc fb fb fb fb ffff8801c61b1080: fb fb fb fb fc fc fc fc fb fb fb fb fb fb fb fb >ffff8801c61b1100: fc fc fc fc fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff8801c61b1180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8801c61b1200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================