================================================================== BUG: KASAN: use-after-free in con_shutdown+0x65/0x80 drivers/tty/vt/vt.c:3278 Write of size 8 at addr ffff8880460ae108 by task syz-executor.1/28186 CPU: 1 PID: 28186 Comm: syz-executor.1 Not tainted 5.6.0-rc1-syzkaller #0 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+0x1fb/0x318 lib/dump_stack.c:118 print_address_description+0x74/0x5c0 mm/kasan/report.c:374 __kasan_report+0x149/0x1c0 mm/kasan/report.c:506 kasan_report+0x26/0x50 mm/kasan/common.c:641 __asan_report_store8_noabort+0x17/0x20 mm/kasan/generic_report.c:140 con_shutdown+0x65/0x80 drivers/tty/vt/vt.c:3278 release_tty+0xc1/0x530 drivers/tty/tty_io.c:1514 tty_release_struct+0xc3/0xe0 drivers/tty/tty_io.c:1629 tty_release+0xceb/0xfb0 drivers/tty/tty_io.c:1789 __fput+0x2e4/0x740 fs/file_table.c:280 ____fput+0x15/0x20 fs/file_table.c:313 task_work_run+0x176/0x1b0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop arch/x86/entry/common.c:164 [inline] prepare_exit_to_usermode+0x480/0x5b0 arch/x86/entry/common.c:195 syscall_return_slowpath+0x113/0x4a0 arch/x86/entry/common.c:278 do_syscall_64+0x11f/0x1c0 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x414f51 Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007fff67c81f00 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000414f51 RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000760150 R09: ffffffffffffffff R10: 00007fff67c81fd0 R11: 0000000000000293 R12: 000000000075bf20 R13: 0000000000000003 R14: 0000000000760158 R15: 000000000075bf2c Allocated by task 28195: save_stack mm/kasan/common.c:72 [inline] set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc+0x118/0x1c0 mm/kasan/common.c:515 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529 kmem_cache_alloc_trace+0x221/0x2f0 mm/slab.c:3551 kmalloc include/linux/slab.h:555 [inline] kzalloc include/linux/slab.h:669 [inline] vc_allocate+0x161/0x5b0 drivers/tty/vt/vt.c:1085 con_install+0x4b/0x490 drivers/tty/vt/vt.c:3229 tty_driver_install_tty drivers/tty/tty_io.c:1228 [inline] tty_init_dev+0xcd/0x500 drivers/tty/tty_io.c:1341 tty_open_by_driver drivers/tty/tty_io.c:1987 [inline] tty_open+0x7f0/0xcd0 drivers/tty/tty_io.c:2035 chrdev_open+0x509/0x590 fs/char_dev.c:414 do_dentry_open+0x85b/0x10c0 fs/open.c:797 vfs_open+0x73/0x80 fs/open.c:914 do_last fs/namei.c:3490 [inline] path_openat+0x16f1/0x4380 fs/namei.c:3607 do_filp_open+0x192/0x3d0 fs/namei.c:3637 do_sys_openat2+0x42b/0x6f0 fs/open.c:1149 do_sys_open fs/open.c:1165 [inline] ksys_open include/linux/syscalls.h:1386 [inline] __do_sys_open fs/open.c:1171 [inline] __se_sys_open fs/open.c:1169 [inline] __x64_sys_open+0x1bd/0x1e0 fs/open.c:1169 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 28199: save_stack mm/kasan/common.c:72 [inline] set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:337 [inline] __kasan_slab_free+0x12e/0x1e0 mm/kasan/common.c:476 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485 __cache_free mm/slab.c:3426 [inline] kfree+0x10d/0x220 mm/slab.c:3757 vt_disallocate_all drivers/tty/vt/vt_ioctl.c:323 [inline] vt_ioctl+0x229d/0x3a70 drivers/tty/vt/vt_ioctl.c:816 tty_ioctl+0xee6/0x15c0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl fs/ioctl.c:763 [inline] __do_sys_ioctl fs/ioctl.c:772 [inline] __se_sys_ioctl+0x113/0x190 fs/ioctl.c:770 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:770 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8880460ae000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 264 bytes inside of 2048-byte region [ffff8880460ae000, ffff8880460ae800) The buggy address belongs to the page: page:ffffea0001182b80 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea0001748b08 ffffea0001151a88 ffff8880aa400e00 raw: 0000000000000000 ffff8880460ae000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880460ae000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880460ae080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880460ae100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880460ae180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880460ae200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================