================================================================== BUG: KASAN: use-after-free in con_shutdown+0x61/0x80 drivers/tty/vt/vt.c:3287 Write of size 8 at addr ffff888095fc0108 by task syz-executor.3/18491 CPU: 0 PID: 18491 Comm: syz-executor.3 Not tainted 5.6.0-rc5-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+0x1e9/0x30e lib/dump_stack.c:118 print_address_description+0x74/0x5c0 mm/kasan/report.c:374 __kasan_report+0x14b/0x1c0 mm/kasan/report.c:506 kasan_report+0x25/0x50 mm/kasan/common.c:641 con_shutdown+0x61/0x80 drivers/tty/vt/vt.c:3287 release_tty+0xb9/0x530 drivers/tty/tty_io.c:1514 tty_release_struct+0xb8/0xd0 drivers/tty/tty_io.c:1629 tty_release+0xe23/0x1100 drivers/tty/tty_io.c:1789 __fput+0x2d8/0x730 fs/file_table.c:280 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+0x48e/0x600 arch/x86/entry/common.c:195 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x416211 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:00007ffe850e0f80 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000416211 RDX: 0000001b32b20000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 0000000000000001 R08: 00000000a4bdfcdf R09: 00000000a4bdfce3 R10: 00007ffe850e1060 R11: 0000000000000293 R12: 000000000076c900 R13: 000000000076c900 R14: 0000000000056500 R15: 000000000076bfac Allocated by task 18492: 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 kmem_cache_alloc_trace+0x234/0x300 mm/slab.c:3551 kmalloc include/linux/slab.h:555 [inline] kzalloc include/linux/slab.h:669 [inline] vc_allocate+0x148/0x5b0 drivers/tty/vt/vt.c:1096 con_install+0x48/0x460 drivers/tty/vt/vt.c:3238 tty_driver_install_tty drivers/tty/tty_io.c:1228 [inline] tty_init_dev+0xc6/0x4c0 drivers/tty/tty_io.c:1341 tty_open_by_driver drivers/tty/tty_io.c:1987 [inline] tty_open+0x7cd/0xca0 drivers/tty/tty_io.c:2035 chrdev_open+0x498/0x580 fs/char_dev.c:414 do_dentry_open+0x828/0x10a0 fs/open.c:797 do_last fs/namei.c:3490 [inline] path_openat+0x13b5/0x40d0 fs/namei.c:3607 do_filp_open+0x191/0x3a0 fs/namei.c:3637 do_sys_openat2+0x448/0x6c0 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+0x1af/0x1e0 fs/open.c:1169 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 18494: 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 __cache_free mm/slab.c:3426 [inline] kfree+0x10a/0x220 mm/slab.c:3757 vt_disallocate_all drivers/tty/vt/vt_ioctl.c:323 [inline] vt_ioctl+0x229d/0x3a30 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+0xf9/0x160 fs/ioctl.c:770 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff888095fc0000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 264 bytes inside of 2048-byte region [ffff888095fc0000, ffff888095fc0800) The buggy address belongs to the page: page:ffffea000257f000 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea00028d9608 ffffea0002624888 ffff8880aa400e00 raw: 0000000000000000 ffff888095fc0000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888095fc0000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888095fc0080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888095fc0100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888095fc0180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888095fc0200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================