================================================================== BUG: KASAN: use-after-free in fbcon_cursor+0x57a/0x660 drivers/video/fbdev/core/fbcon.c:1389 Read of size 2 at addr ffff888218bad2bc by task syz-executor.3/2459 CPU: 1 PID: 2459 Comm: syz-executor.3 Not tainted 5.8.0-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+0x18f/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530 fbcon_cursor+0x57a/0x660 drivers/video/fbdev/core/fbcon.c:1389 fbcon_scrolldelta+0x22c/0x1230 drivers/video/fbdev/core/fbcon.c:2887 fbcon_set_origin+0x3c/0x50 drivers/video/fbdev/core/fbcon.c:2938 set_origin+0xe7/0x3e0 drivers/tty/vt/vt.c:930 vc_do_resize+0xb2f/0x1180 drivers/tty/vt/vt.c:1305 vt_ioctl+0x1147/0x2c20 drivers/tty/vt/vt_ioctl.c:1015 tty_ioctl+0x1019/0x15f0 drivers/tty/tty_io.c:2656 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d239 Code: 5d b4 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 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fc738a97c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 000000000001c300 RCX: 000000000045d239 RDX: 0000000020000040 RSI: 0000000000005609 RDI: 0000000000000005 RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c R13: 00007ffe9c89142f R14: 00007fc738a989c0 R15: 000000000118cf4c Allocated by task 1: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 kasan_set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461 __do_kmalloc mm/slab.c:3655 [inline] __kmalloc+0x1a8/0x320 mm/slab.c:3664 kmalloc include/linux/slab.h:559 [inline] kzalloc include/linux/slab.h:666 [inline] vc_do_resize+0x2f6/0x1180 drivers/tty/vt/vt.c:1228 fbcon_init+0x1319/0x1b00 drivers/video/fbdev/core/fbcon.c:1218 visual_init+0x30e/0x5d0 drivers/tty/vt/vt.c:1074 do_bind_con_driver.isra.0+0x549/0x8e0 drivers/tty/vt/vt.c:3657 do_take_over_console+0x423/0x570 drivers/tty/vt/vt.c:4237 do_fbcon_takeover+0x10b/0x210 drivers/video/fbdev/core/fbcon.c:588 fbcon_fb_registered+0x26b/0x340 drivers/video/fbdev/core/fbcon.c:3262 do_register_framebuffer drivers/video/fbdev/core/fbmem.c:1660 [inline] register_framebuffer+0x587/0x980 drivers/video/fbdev/core/fbmem.c:1828 vga16fb_probe+0x6b4/0x7b5 drivers/video/fbdev/vga16fb.c:1373 platform_drv_probe+0x87/0x140 drivers/base/platform.c:747 really_probe+0x282/0x9f0 drivers/base/dd.c:553 driver_probe_device+0xfe/0x1d0 drivers/base/dd.c:738 __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:844 bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:431 __device_attach+0x228/0x470 drivers/base/dd.c:912 bus_probe_device+0x1e4/0x290 drivers/base/bus.c:491 device_add+0xb17/0x1c40 drivers/base/core.c:2930 platform_device_add+0x34f/0x6d0 drivers/base/platform.c:597 vga16fb_init+0x152/0x1c8 drivers/video/fbdev/vga16fb.c:1431 do_one_initcall+0x10a/0x7a4 init/main.c:1204 do_initcall_level init/main.c:1277 [inline] do_initcalls init/main.c:1293 [inline] do_basic_setup init/main.c:1313 [inline] kernel_init_freeable+0x59c/0x620 init/main.c:1512 kernel_init+0xd/0x1c0 init/main.c:1402 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Freed by task 2459: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 kasan_set_track+0x1c/0x30 mm/kasan/common.c:56 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355 __kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422 __cache_free mm/slab.c:3418 [inline] kfree+0x103/0x2c0 mm/slab.c:3756 vc_do_resize+0xacf/0x1180 drivers/tty/vt/vt.c:1302 vt_ioctl+0x1147/0x2c20 drivers/tty/vt/vt_ioctl.c:1015 tty_ioctl+0x1019/0x15f0 drivers/tty/tty_io.c:2656 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The buggy address belongs to the object at ffff888218bac000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 4796 bytes inside of 8192-byte region [ffff888218bac000, ffff888218bae000) The buggy address belongs to the page: page:00000000777804fb refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x218bac head:00000000777804fb order:2 compound_mapcount:0 compound_pincount:0 flags: 0x57ffe0000010200(slab|head) raw: 057ffe0000010200 ffffea0008653e08 ffffea0008604a08 ffff8880aa040a00 raw: 0000000000000000 ffff888218bac000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888218bad180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888218bad200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888218bad280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888218bad300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888218bad380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================