bisecting fixing commit since 6794862a16ef41f753abd75c03a152836e4c8028
building syzkaller on 5a5826a14e99564bdd4de163d3ac368056e5d992
testing commit 6794862a16ef41f753abd75c03a152836e4c8028 with gcc (GCC) 8.1.0
kernel signature: bb63f76d2f5fa51064738042fd531927d760dcd259efbd78f2eab97fef229016
all runs: crashed: KASAN: wild-memory-access Read in insert_char
testing current HEAD b19e8c68470385dd2c5440876591fddb02c8c402
testing commit b19e8c68470385dd2c5440876591fddb02c8c402 with gcc (GCC) 8.1.0
kernel signature: c96995197e19101fc0ea26821952bafae5ef0710f46bdcb965c5001a2b9d0502
all runs: crashed: KASAN: wild-memory-access Read in insert_char
revisions tested: 2, total time: 21m36.363758714s (build: 12m52.736263054s, test: 7m55.296309665s)
the crash still happens on HEAD
commit msg: Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
crash: KASAN: wild-memory-access Read in insert_char
==================================================================
BUG: KASAN: wild-memory-access in memmove include/linux/string.h:396 [inline]
BUG: KASAN: wild-memory-access in scr_memmovew include/linux/vt_buffer.h:68 [inline]
BUG: KASAN: wild-memory-access in insert_char+0x1e2/0x3e0 drivers/tty/vt/vt.c:839
Read of size 212 at addr 00000000ffffff3a by task syz-executor.4/8132

CPU: 1 PID: 8132 Comm: syz-executor.4 Not tainted 5.6.0-rc1-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+0x12d/0x187 lib/dump_stack.c:118
 __kasan_report.cold.11+0x5/0x32 mm/kasan/report.c:510
 kasan_report+0x12/0x20 mm/kasan/common.c:641
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x153/0x1d0 mm/kasan/generic.c:192
 memmove+0x23/0x50 mm/kasan/common.c:117
 memmove include/linux/string.h:396 [inline]
 scr_memmovew include/linux/vt_buffer.h:68 [inline]
 insert_char+0x1e2/0x3e0 drivers/tty/vt/vt.c:839
 csi_at drivers/tty/vt/vt.c:1964 [inline]
 do_con_trol+0x5742/0x63d0 drivers/tty/vt/vt.c:2431
 do_con_write.part.25+0xab6/0x1ad0 drivers/tty/vt/vt.c:2797
 do_con_write drivers/tty/vt/vt.c:2565 [inline]
 con_write+0x1f/0x80 drivers/tty/vt/vt.c:3135
 process_output_block drivers/tty/n_tty.c:595 [inline]
 n_tty_write+0x494/0xfa0 drivers/tty/n_tty.c:2333
 do_tty_write drivers/tty/tty_io.c:962 [inline]
 tty_write+0x371/0x7d0 drivers/tty/tty_io.c:1046
 __vfs_write+0x5e/0x110 fs/read_write.c:494
 vfs_write+0x18a/0x520 fs/read_write.c:558
 ksys_write+0x105/0x220 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __ia32_sys_write+0x6c/0xa0 fs/read_write.c:620
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x235/0xb68 arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7fb7e49
Code: 1d 00 00 00 89 d3 eb e0 8b 04 24 c3 8b 34 24 c3 8b 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000f7f910cc EFLAGS: 00000296 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000020000000
RDX: 0000000000000078 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
==================================================================