bisecting fixing commit since c7ecf3e3a71c216327980f26b1e895ce9b07ad31
building syzkaller on 25a0186eba20ef6f4f657039ff02eff52a838b1c
testing commit c7ecf3e3a71c216327980f26b1e895ce9b07ad31 with gcc (GCC) 8.1.0
kernel signature: 1afd359e7ac2327abbb22ec1ae684f0ba70b6d30b4601e8d90afac45fd494ada
all runs: crashed: KASAN: global-out-of-bounds Read in fbcon_get_font
testing current HEAD a87f96283793d58b042618c689630db264715274
testing commit a87f96283793d58b042618c689630db264715274 with gcc (GCC) 8.1.0
kernel signature: eb65047588dab6cad50956073449daf469b8d4cbe01049a4ccc6a95ace06dfa5
all runs: crashed: KASAN: global-out-of-bounds Read in fbcon_get_font
revisions tested: 2, total time: 23m19.958303767s (build: 16m34.932600579s, test: 5m55.290990111s)
the crash still happens on HEAD
commit msg: Linux 4.19.145
crash: KASAN: global-out-of-bounds Read in fbcon_get_font
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_hsr: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth1_to_hsr: link is not ready
==================================================================
BUG: KASAN: global-out-of-bounds in memcpy include/linux/string.h:373 [inline]
BUG: KASAN: global-out-of-bounds in fbcon_get_font+0x298/0x6a0 drivers/video/fbdev/core/fbcon.c:2467
Read of size 32 at addr ffffffff876954a0 by task syz-executor.2/7484

CPU: 1 PID: 7484 Comm: syz-executor.2 Not tainted 4.19.145-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+0x123/0x177 lib/dump_stack.c:118
 print_address_description.cold.8+0x58/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 memcpy+0x23/0x50 mm/kasan/kasan.c:302
 memcpy include/linux/string.h:373 [inline]
 fbcon_get_font+0x298/0x6a0 drivers/video/fbdev/core/fbcon.c:2467
 con_font_get drivers/tty/vt/vt.c:4445 [inline]
 con_font_op+0x3a4/0x11f0 drivers/tty/vt/vt.c:4604
 do_fontx_ioctl drivers/tty/vt/vt_ioctl.c:265 [inline]
 vt_ioctl+0xdce/0x23f0 drivers/tty/vt/vt_ioctl.c:955
 tty_ioctl+0x452/0x1290 drivers/tty/tty_io.c:2669
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0x196/0x10c0 fs/ioctl.c:688
 ksys_ioctl+0x62/0x90 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:710
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45aa69
Code: 2d b6 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 fb b5 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f7085ae8c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045aa69
RDX: 0000000020000200 RSI: 0000000000004b60 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f7085ae96d4
R13: 00000000004c5c48 R14: 00000000004dc270 R15: 00000000ffffffff

The buggy address belongs to the variable:
 fontdata_8x16+0x1000/0x1120

Memory state around the buggy address:
 ffffffff87695380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffff87695400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffffff87695480: 00 00 00 00 fa fa fa fa 06 fa fa fa fa fa fa fa
                               ^
 ffffffff87695500: 05 fa fa fa fa fa fa fa 06 fa fa fa fa fa fa fa
 ffffffff87695580: 00 00 03 fa fa fa fa fa 00 00 00 00 00 00 00 00
==================================================================