================================================================== BUG: KASAN: use-after-free in fbcon_cursor+0x5c5/0x760 drivers/video/fbdev/core/fbcon.c:1350 Read of size 2 at addr ffff888219768bd8 by task syz-executor.5/1663 CPU: 0 PID: 1663 Comm: syz-executor.5 Not tainted 4.19.124-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+0x1fc/0x2fe lib/dump_stack.c:118 print_address_description.cold+0x54/0x222 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report mm/kasan/report.c:412 [inline] kasan_report.cold+0x88/0x2b9 mm/kasan/report.c:396 fbcon_cursor+0x5c5/0x760 drivers/video/fbdev/core/fbcon.c:1350 fbcon_scrolldelta+0x39c/0x12d0 drivers/video/fbdev/core/fbcon.c:2858 fbcon_set_origin+0x3c/0x50 drivers/video/fbdev/core/fbcon.c:2909 set_origin+0x32e/0x430 drivers/tty/vt/vt.c:926 vc_do_resize+0x9dc/0x1380 drivers/tty/vt/vt.c:1297 vt_ioctl+0x1fa2/0x2500 drivers/tty/vt/vt_ioctl.c:901 tty_ioctl+0x7a5/0x1420 drivers/tty/tty_io.c:2669 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0xcda/0x12e0 fs/ioctl.c:688 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45ca29 Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f533b3bdc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000004f2b00 RCX: 000000000045ca29 RDX: 0000000020000000 RSI: 000000000000560a RDI: 0000000000000005 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000673 R14: 00000000004c9681 R15: 00007f533b3be6d4 Allocated by task 1: __do_kmalloc mm/slab.c:3727 [inline] __kmalloc+0x15a/0x3c0 mm/slab.c:3736 kmalloc include/linux/slab.h:520 [inline] kzalloc include/linux/slab.h:709 [inline] vc_do_resize+0x245/0x1380 drivers/tty/vt/vt.c:1220 fbcon_init+0x1043/0x1b00 drivers/video/fbdev/core/fbcon.c:1179 visual_init+0x332/0x5f0 drivers/tty/vt/vt.c:1072 do_bind_con_driver+0x53b/0x8c0 drivers/tty/vt/vt.c:3544 do_take_over_console+0x453/0x5a0 drivers/tty/vt/vt.c:4105 do_fbcon_takeover+0x10b/0x210 drivers/video/fbdev/core/fbcon.c:556 fbcon_fb_registered drivers/video/fbdev/core/fbcon.c:3231 [inline] fbcon_event_notify+0x1798/0x1d60 drivers/video/fbdev/core/fbcon.c:3361 notifier_call_chain+0xc0/0x230 kernel/notifier.c:93 __blocking_notifier_call_chain kernel/notifier.c:317 [inline] __blocking_notifier_call_chain kernel/notifier.c:304 [inline] blocking_notifier_call_chain kernel/notifier.c:328 [inline] blocking_notifier_call_chain+0x85/0xa0 kernel/notifier.c:325 do_register_framebuffer drivers/video/fbdev/core/fbmem.c:1708 [inline] register_framebuffer+0x5c5/0x9e0 drivers/video/fbdev/core/fbmem.c:1831 vga16fb_probe+0x6da/0x7ea drivers/video/fbdev/vga16fb.c:1373 platform_drv_probe+0x8d/0x160 drivers/base/platform.c:584 really_probe+0x473/0x640 drivers/base/dd.c:503 driver_probe_device+0xf9/0x200 drivers/base/dd.c:664 __device_attach_driver+0x21c/0x290 drivers/base/dd.c:751 bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:464 __device_attach+0x21e/0x320 drivers/base/dd.c:817 bus_probe_device+0x1ea/0x2a0 drivers/base/bus.c:524 device_add+0xadd/0x1650 drivers/base/core.c:2154 platform_device_add+0x355/0x6e0 drivers/base/platform.c:420 vga16fb_init+0x152/0x1c8 drivers/video/fbdev/vga16fb.c:1431 do_one_initcall+0xf1/0x734 init/main.c:885 do_initcall_level init/main.c:953 [inline] do_initcalls init/main.c:961 [inline] do_basic_setup init/main.c:979 [inline] kernel_init_freeable+0x9ac/0xa9e init/main.c:1146 kernel_init+0xd/0x1b8 init/main.c:1063 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Freed by task 1663: __cache_free mm/slab.c:3503 [inline] kfree+0xce/0x220 mm/slab.c:3822 vc_do_resize+0x97c/0x1380 drivers/tty/vt/vt.c:1294 vt_ioctl+0x1fa2/0x2500 drivers/tty/vt/vt_ioctl.c:901 tty_ioctl+0x7a5/0x1420 drivers/tty/tty_io.c:2669 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0xcda/0x12e0 fs/ioctl.c:688 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8882197681c0 which belongs to the cache kmalloc-8192 of size 8192 The buggy address is located 2584 bytes inside of 8192-byte region [ffff8882197681c0, ffff88821976a1c0) The buggy address belongs to the page: page:ffffea000865da00 count:1 mapcount:0 mapping:ffff88812c3d5080 index:0x0 compound_mapcount: 0 flags: 0x57ffe0000008100(slab|head) raw: 057ffe0000008100 ffffea000865c808 ffffea0008628908 ffff88812c3d5080 raw: 0000000000000000 ffff8882197681c0 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888219768a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888219768b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888219768b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888219768c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888219768c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================