================================================================== BUG: KASAN: use-after-free in con_shutdown+0x7f/0x90 drivers/tty/vt/vt.c:2928 Write of size 8 at addr ffff888055140a08 by task syz-executor.3/9076 CPU: 1 PID: 9076 Comm: syz-executor.3 Not tainted 4.14.174-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x13e/0x194 lib/dump_stack.c:58 print_address_description.cold+0x7c/0x1e2 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report mm/kasan/report.c:409 [inline] kasan_report.cold+0xa9/0x2ae mm/kasan/report.c:393 con_shutdown+0x7f/0x90 drivers/tty/vt/vt.c:2928 release_tty+0xb6/0x7a0 drivers/tty/tty_io.c:1501 tty_release_struct+0x37/0x50 drivers/tty/tty_io.c:1616 tty_release+0xaa6/0xd60 drivers/tty/tty_io.c:1776 __fput+0x25f/0x790 fs/file_table.c:210 task_work_run+0x113/0x190 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x9f2/0x2b00 kernel/exit.c:858 do_group_exit+0x100/0x310 kernel/exit.c:955 SYSC_exit_group kernel/exit.c:966 [inline] SyS_exit_group+0x19/0x20 kernel/exit.c:964 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45c849 RSP: 002b:00007f0c6829bb78 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 000000000000000d RCX: 000000000045c849 RDX: 0000000000416321 RSI: 0000000000c870f0 RDI: 0000000000000000 RBP: 00000000004cfee8 R08: 000000000000000c R09: 0000000000000000 R10: 00007f0c6829c700 R11: 0000000000000246 R12: 00000000ffffffff R13: 000000000000037c R14: 00000000004c5ee3 R15: 0000000000000000 Allocated by task 9076: save_stack+0x32/0xa0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc mm/kasan/kasan.c:551 [inline] kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:529 kmem_cache_alloc_trace+0x14d/0x7b0 mm/slab.c:3618 kmalloc include/linux/slab.h:488 [inline] kzalloc include/linux/slab.h:661 [inline] vc_allocate drivers/tty/vt/vt.c:772 [inline] vc_allocate+0x142/0x550 drivers/tty/vt/vt.c:753 con_install+0x4f/0x3e0 drivers/tty/vt/vt.c:2879 tty_driver_install_tty drivers/tty/tty_io.c:1225 [inline] tty_init_dev drivers/tty/tty_io.c:1338 [inline] tty_init_dev+0xe1/0x3a0 drivers/tty/tty_io.c:1315 tty_open_by_driver drivers/tty/tty_io.c:1973 [inline] tty_open+0x410/0x9c0 drivers/tty/tty_io.c:2021 chrdev_open+0x1fc/0x540 fs/char_dev.c:423 do_dentry_open+0x732/0xe90 fs/open.c:777 vfs_open+0x105/0x220 fs/open.c:888 do_last fs/namei.c:3428 [inline] path_openat+0x8ca/0x3c50 fs/namei.c:3569 do_filp_open+0x18e/0x250 fs/namei.c:3603 do_sys_open+0x29d/0x3f0 fs/open.c:1081 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 Freed by task 9078: save_stack+0x32/0xa0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kfree+0xcb/0x260 mm/slab.c:3815 vt_disallocate_all+0x25c/0x340 drivers/tty/vt/vt_ioctl.c:323 vt_ioctl+0x6e3/0x1f00 drivers/tty/vt/vt_ioctl.c:816 tty_ioctl+0x6c5/0x1220 drivers/tty/tty_io.c:2661 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 The buggy address belongs to the object at ffff888055140900 which belongs to the cache kmalloc-2048 of size 2048 The buggy address is located 264 bytes inside of 2048-byte region [ffff888055140900, ffff888055141100) The buggy address belongs to the page: page:ffffea0001545000 count:1 mapcount:0 mapping:ffff888055140080 index:0x0 compound_mapcount: 0 flags: 0xfffe0000008100(slab|head) raw: 00fffe0000008100 ffff888055140080 0000000000000000 0000000100000003 raw: ffffea00015429a0 ffffea0001545ba0 ffff88812fe56c40 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888055140900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888055140980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888055140a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888055140a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888055140b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================