bisecting fixing commit since daefdc9eb24bfa11ab77a4b2a9c3923f1051fe0b
building syzkaller on f12ba0c59fb470378fd054bba8ce424156c4f164
testing commit daefdc9eb24bfa11ab77a4b2a9c3923f1051fe0b with gcc (GCC) 8.4.1 20210217
kernel signature: 20ea7406448a6f6fc794d3acc59a90b3e9243fb3aaa7707ba8ad6068e33bf15f
all runs: crashed: KASAN: global-out-of-bounds Read in soft_cursor
testing current HEAD 255b58a2b3af0baa0ee11507390349217b8b73b0
testing commit 255b58a2b3af0baa0ee11507390349217b8b73b0 with gcc (GCC) 8.4.1 20210217
kernel signature: 82f2d2553c9c89f85dd89ef8becbd242938755aa6600cb14dfc519d91fa93aaa
all runs: crashed: KASAN: global-out-of-bounds Read in soft_cursor
revisions tested: 2, total time: 21m46.807577658s (build: 14m25.390737939s, test: 6m27.957415815s)
the crash still happens on HEAD
commit msg: Linux 4.19.176
crash: KASAN: global-out-of-bounds Read in soft_cursor
wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready
wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
==================================================================
BUG: KASAN: global-out-of-bounds in memcpy include/linux/string.h:377 [inline]
BUG: KASAN: global-out-of-bounds in soft_cursor+0x430/0xc70 drivers/video/fbdev/core/softcursor.c:70
Read of size 32 at addr ffffffff88528150 by task syz-executor.2/9840

CPU: 1 PID: 9840 Comm: syz-executor.2 Not tainted 4.19.176-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+0x17c/0x226 lib/dump_stack.c:118
 print_address_description.cold.6+0x12f/0x211 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.7+0x242/0x2fe mm/kasan/report.c:396
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13c/0x1b0 mm/kasan/kasan.c:267
 memcpy+0x23/0x50 mm/kasan/kasan.c:302
 memcpy include/linux/string.h:377 [inline]
 soft_cursor+0x430/0xc70 drivers/video/fbdev/core/softcursor.c:70
 bit_cursor+0xdca/0x1d40 drivers/video/fbdev/core/bitblit.c:377
 fbcon_cursor+0x452/0x660 drivers/video/fbdev/core/fbcon.c:1309
 hide_cursor+0x73/0x2b0 drivers/tty/vt/vt.c:902
 update_region+0x11d/0x170 drivers/tty/vt/vt.c:700
 vcs_write+0x2dd/0xb10 drivers/tty/vt/vc_screen.c:604
 __vfs_write+0xe3/0x890 fs/read_write.c:485
 vfs_write+0x150/0x4d0 fs/read_write.c:549
 ksys_write+0x103/0x260 fs/read_write.c:599
 __do_sys_write fs/read_write.c:611 [inline]
 __se_sys_write fs/read_write.c:608 [inline]
 __x64_sys_write+0x6e/0xb0 fs/read_write.c:608
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4657f9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1c27add188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000055bf00 RCX: 00000000004657f9
RDX: 0000000000000121 RSI: 00000000200000c0 RDI: 0000000000000004
RBP: 00000000004af682 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf00
R13: 00007ffd08dabb2f R14: 00007f1c27add300 R15: 0000000000022000

The buggy address belongs to the variable:
 oid_index+0x850/0xa60

Memory state around the buggy address:
 ffffffff88528000: fa fa fa fa 04 fa fa fa fa fa fa fa 04 fa fa fa
 ffffffff88528080: fa fa fa fa 07 fa fa fa fa fa fa fa 04 fa fa fa
>ffffffff88528100: fa fa fa fa 05 fa fa fa fa fa fa fa 01 fa fa fa
                                                 ^
 ffffffff88528180: fa fa fa fa 00 00 02 fa fa fa fa fa 00 00 00 fa
 ffffffff88528200: fa fa fa fa 00 00 00 00 00 01 fa fa fa fa fa fa
==================================================================