KASAN: global-out-of-bounds Read in soft_cursor

Status: auto-closed as invalid on 2020/11/22 03:01
Subsystems: fbdev
[Documentation on labels]
Reported-by: syzbot+88dbe7c16ff8616b3720@syzkaller.appspotmail.com
First crash: 2442d, last: 2217d
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
KASAN: global-out-of-bounds Read in soft_cursor 0 (1) 2019/12/12 08:58
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-out-of-bounds Read in soft_cursor (2) fbdev 17 9 198d 331d 0/29 auto-obsoleted due to no activity on 2026/05/14 02:42
upstream KASAN: global-out-of-bounds Read in soft_cursor (3) fbdev 19 31 7m 13d 24/29 upstream: reported on 2026/08/07 00:01
upstream KASAN: global-out-of-bounds Read in soft_cursor (2) fbdev 17 1 544d 540d 0/29 auto-obsoleted due to no activity on 2025/05/23 01:13
linux-4.19 KASAN: global-out-of-bounds Read in soft_cursor 17 syz, C done 22 1913d 2380d 1/1 fixed on 2021/06/24 08:01
linux-4.14 KASAN: global-out-of-bounds Read in soft_cursor 17 syz, C error 19 1439d 2439d 0/1 upstream: reported C repro on 2019/12/16 00:09

Sample crash report:
==================================================================
BUG: KASAN: global-out-of-bounds in memcpy include/linux/string.h:406 [inline]
BUG: KASAN: global-out-of-bounds in soft_cursor+0x44b/0xa30 drivers/video/fbdev/core/softcursor.c:70
Read of size 26 at addr ffffffff88965288 by task syz-executor.4/5256

CPU: 0 PID: 5256 Comm: syz-executor.4 Not tainted 5.8.0-rc6-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+0x5/0x436 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 check_memory_region_inline mm/kasan/generic.c:186 [inline]
 check_memory_region+0x13d/0x180 mm/kasan/generic.c:192
 memcpy+0x20/0x60 mm/kasan/common.c:105
 memcpy include/linux/string.h:406 [inline]
 soft_cursor+0x44b/0xa30 drivers/video/fbdev/core/softcursor.c:70
 bit_cursor+0x1166/0x17d0 drivers/video/fbdev/core/bitblit.c:386
 fbcon_cursor+0x52b/0x650 drivers/video/fbdev/core/fbcon.c:1411
 hide_cursor+0x85/0x280 drivers/tty/vt/vt.c:902
 redraw_screen+0x5e1/0x770 drivers/tty/vt/vt.c:1006
 fbcon_do_set_font+0x7ec/0x950 drivers/video/fbdev/core/fbcon.c:2615
 fbcon_copy_font+0x125/0x190 drivers/video/fbdev/core/fbcon.c:2630
 con_font_copy drivers/tty/vt/vt.c:4627 [inline]
 con_font_op+0x65a/0x1110 drivers/tty/vt/vt.c:4642
 vt_ioctl+0x16dc/0x2670 drivers/tty/vt/vt_ioctl.c:980
 tty_ioctl+0x1019/0x15f0 drivers/tty/tty_io.c:2656
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl fs/ioctl.c:760 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45c1f9
Code: Bad RIP value.
RSP: 002b:00007fb0c4340c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000000f440 RCX: 000000000045c1f9
RDX: 0000000020000480 RSI: 0000000000004b72 RDI: 0000000000000007
RBP: 000000000078bfe0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bfac
R13: 00007fff87f33a2f R14: 00007fb0c43419c0 R15: 000000000078bfac

The buggy address belongs to the variable:
 oid_search_table+0x128/0x160

Memory state around the buggy address:
 ffffffff88965180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffff88965200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffffff88965280: 00 fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
                      ^
 ffffffff88965300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffff88965380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (11):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/07/25 03:00 upstream f37e99aca03f 554af388 .config console log report ci-upstream-kasan-gce-root
2020/06/06 13:11 upstream 7ae77150d94d e6b89e4e .config console log report ci-upstream-kasan-gce-root
2020/04/24 17:32 upstream b4f633221f0a 03d97a1b .config console log report ci-upstream-kasan-gce-selinux-root
2020/02/18 21:52 upstream b1da3acc781c 012fbc32 .config console log report ci-upstream-kasan-gce-selinux-root
2020/01/14 19:50 upstream 452424cdcbca fa12bd3c .config console log report ci-qemu-upstream
2020/01/11 16:20 upstream bef1d88263ff 4c04afaa .config console log report ci-upstream-kasan-gce-root
2019/12/29 21:32 upstream a99efa00891b af6b8ef8 .config console log report ci-upstream-kasan-gce-root
2019/12/12 07:36 upstream 687dec9b9459 d973f528 .config console log report ci-upstream-kasan-gce-root
2020/06/10 01:36 linux-next e7b08814b16b 860c4de9 .config console log report ci-upstream-linux-next-kasan-gce-root
2020/03/10 21:45 linux-next 770fbb32d34e 35f53e45 .config console log report ci-upstream-linux-next-kasan-gce-root
2019/12/16 18:50 linux-next 32b8acf85223 b80769fc .config console log report ci-upstream-linux-next-kasan-gce-root
* Struck through repros no longer work on HEAD.