================================================================== BUG: KASAN: use-after-free in ip4_string+0x471/0x4d0 lib/vsprintf.c:1261 Read of size 1 at addr ffff8880899eca9a by task syz-executor.0/9516 CPU: 1 PID: 9516 Comm: syz-executor.0 Not tainted 5.2.0-rc4+ #25 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 kasan_report+0x12/0x20 mm/kasan/common.c:614 __asan_report_load1_noabort+0x14/0x20 mm/kasan/generic_report.c:129 ip4_string+0x471/0x4d0 lib/vsprintf.c:1261 ip4_addr_string+0x8b/0xd0 lib/vsprintf.c:1399 ip_addr_string+0x2bd/0x440 lib/vsprintf.c:1514 pointer+0x16c/0x750 lib/vsprintf.c:2149 vsnprintf+0x6b6/0x19a0 lib/vsprintf.c:2507 sprintf+0xc0/0x100 lib/vsprintf.c:2705 arp_format_pneigh_entry net/ipv4/arp.c:1379 [inline] arp_seq_show+0x493/0x9d0 net/ipv4/arp.c:1394 seq_read+0x4ca/0x1110 fs/seq_file.c:229 proc_reg_read+0x1fc/0x2c0 fs/proc/inode.c:221 do_loop_readv_writev fs/read_write.c:714 [inline] do_loop_readv_writev fs/read_write.c:701 [inline] do_iter_read+0x4a4/0x660 fs/read_write.c:935 vfs_readv+0xf0/0x160 fs/read_write.c:997 kernel_readv fs/splice.c:359 [inline] default_file_splice_read+0x475/0x890 fs/splice.c:414 do_splice_to+0x127/0x180 fs/splice.c:877 splice_direct_to_actor+0x2d2/0x970 fs/splice.c:954 do_splice_direct+0x1da/0x2a0 fs/splice.c:1063 do_sendfile+0x597/0xd00 fs/read_write.c:1464 __do_compat_sys_sendfile fs/read_write.c:1546 [inline] __se_compat_sys_sendfile fs/read_write.c:1529 [inline] __ia32_compat_sys_sendfile+0x1f1/0x230 fs/read_write.c:1529 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline] do_fast_syscall_32+0x27b/0xd7d arch/x86/entry/common.c:408 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 RIP: 0023:0xf7f75849 Code: 85 d2 74 02 89 0a 5b 5d c3 8b 04 24 c3 8b 14 24 c3 8b 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 002b:00000000f7f710cc EFLAGS: 00000296 ORIG_RAX: 00000000000000bb RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000000004 RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 9517: save_stack+0x23/0x90 mm/kasan/common.c:71 set_track mm/kasan/common.c:79 [inline] __kasan_kmalloc mm/kasan/common.c:489 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503 __do_kmalloc mm/slab.c:3660 [inline] __kmalloc+0x15c/0x740 mm/slab.c:3669 kmalloc include/linux/slab.h:552 [inline] pneigh_lookup+0x19c/0x4a0 net/core/neighbour.c:731 arp_req_set_public net/ipv4/arp.c:1010 [inline] arp_req_set+0x613/0x720 net/ipv4/arp.c:1026 arp_ioctl+0x652/0x7f0 net/ipv4/arp.c:1226 inet_ioctl+0x2a0/0x340 net/ipv4/af_inet.c:926 sock_do_ioctl+0xd8/0x2f0 net/socket.c:1043 compat_sock_ioctl_trans net/socket.c:3416 [inline] compat_sock_ioctl+0x149b/0x1bf0 net/socket.c:3441 __do_compat_sys_ioctl fs/compat_ioctl.c:1052 [inline] __se_compat_sys_ioctl fs/compat_ioctl.c:998 [inline] __ia32_compat_sys_ioctl+0x195/0x620 fs/compat_ioctl.c:998 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline] do_fast_syscall_32+0x27b/0xd7d arch/x86/entry/common.c:408 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 Freed by task 9514: save_stack+0x23/0x90 mm/kasan/common.c:71 set_track mm/kasan/common.c:79 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459 __cache_free mm/slab.c:3432 [inline] kfree+0xcf/0x220 mm/slab.c:3755 pneigh_ifdown_and_unlock net/core/neighbour.c:812 [inline] __neigh_ifdown+0x236/0x2f0 net/core/neighbour.c:356 neigh_ifdown+0x20/0x30 net/core/neighbour.c:372 arp_ifdown+0x1d/0x21 net/ipv4/arp.c:1274 inetdev_destroy net/ipv4/devinet.c:319 [inline] inetdev_event+0xa14/0x11f0 net/ipv4/devinet.c:1544 notifier_call_chain+0xc2/0x230 kernel/notifier.c:95 __raw_notifier_call_chain kernel/notifier.c:396 [inline] raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:403 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1749 call_netdevice_notifiers_extack net/core/dev.c:1761 [inline] call_netdevice_notifiers net/core/dev.c:1775 [inline] rollback_registered_many+0x9b9/0xfc0 net/core/dev.c:8178 rollback_registered+0x109/0x1d0 net/core/dev.c:8220 unregister_netdevice_queue net/core/dev.c:9267 [inline] unregister_netdevice_queue+0x1ee/0x2c0 net/core/dev.c:9260 unregister_netdevice include/linux/netdevice.h:2631 [inline] __tun_detach+0xd8a/0x1040 drivers/net/tun.c:724 tun_detach drivers/net/tun.c:741 [inline] tun_chr_close+0xe0/0x180 drivers/net/tun.c:3451 __fput+0x2ff/0x890 fs/file_table.c:280 ____fput+0x16/0x20 fs/file_table.c:313 task_work_run+0x145/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:185 [inline] exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:168 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_32_irqs_on arch/x86/entry/common.c:352 [inline] do_fast_syscall_32+0xb51/0xd7d arch/x86/entry/common.c:408 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 The buggy address belongs to the object at ffff8880899eca80 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 26 bytes inside of 64-byte region [ffff8880899eca80, ffff8880899ecac0) The buggy address belongs to the page: page:ffffea0002267b00 refcount:1 mapcount:0 mapping:ffff8880aa400340 index:0x0 flags: 0x1fffc0000000200(slab) raw: 01fffc0000000200 ffffea000263a2c8 ffff8880aa401348 ffff8880aa400340 raw: 0000000000000000 ffff8880899ec000 0000000100000020 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880899ec980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880899eca00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8880899eca80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ^ ffff8880899ecb00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff8880899ecb80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ==================================================================