bisecting fixing commit since 98db2bf27b9ed2d5ed0b6c9c8a4bfcb127a19796
building syzkaller on 5d7b90f1af2e3bf33992b75e7fcf0bab6bf49bd6
testing commit 98db2bf27b9ed2d5ed0b6c9c8a4bfcb127a19796 with gcc (GCC) 8.1.0
kernel signature: 1783ee9a3c2bf5141aafb9a01611344b53d0762cf1f147bb998a77bd5ea4d9ef
all runs: crashed: KASAN: null-ptr-deref Read in do_con_trol
testing current HEAD ab9dfda232481dcfaf549ce774004d116fc80c13
testing commit ab9dfda232481dcfaf549ce774004d116fc80c13 with gcc (GCC) 8.1.0
kernel signature: c9b9876eba7bd4c2b1d37ecf45dd9e650e8b931e598c3f84ebd181a8bf1c1ae0
all runs: crashed: KASAN: null-ptr-deref Read in do_con_trol
revisions tested: 2, total time: 28m10.63728317s (build: 20m41.69876899s, test: 6m3.567283091s)
the crash still happens on HEAD
commit msg: Linux 4.14.180
crash: KASAN: null-ptr-deref Read in do_con_trol
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready
batman_adv: batadv0: Interface activated: batadv_slave_1
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
==================================================================
BUG: KASAN: null-ptr-deref in memcpy include/linux/string.h:347 [inline]
BUG: KASAN: null-ptr-deref in scr_memcpyw include/linux/vt_buffer.h:49 [inline]
BUG: KASAN: null-ptr-deref in delete_char drivers/tty/vt/vt.c:546 [inline]
BUG: KASAN: null-ptr-deref in csi_P drivers/tty/vt/vt.c:1661 [inline]
BUG: KASAN: null-ptr-deref in do_con_trol+0x204c/0x61a0 drivers/tty/vt/vt.c:2035
Read of size 4294967294 at addr 0000000000000012 by task syz-executor.3/7859

CPU: 0 PID: 7859 Comm: syz-executor.3 Not tainted 4.14.180-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xf7/0x13b lib/dump_stack.c:58
 kasan_report_error mm/kasan/report.c:349 [inline]
 kasan_report.cold.8+0x6d/0x2d3 mm/kasan/report.c:409
 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:347 [inline]
 scr_memcpyw include/linux/vt_buffer.h:49 [inline]
 delete_char drivers/tty/vt/vt.c:546 [inline]
 csi_P drivers/tty/vt/vt.c:1661 [inline]
 do_con_trol+0x204c/0x61a0 drivers/tty/vt/vt.c:2035
 do_con_write.part.22+0x9bc/0x19c0 drivers/tty/vt/vt.c:2447
 do_con_write drivers/tty/vt/vt.c:2218 [inline]
 con_write+0x1f/0x80 drivers/tty/vt/vt.c:2798
 process_output_block drivers/tty/n_tty.c:595 [inline]
 n_tty_write+0x498/0x1040 drivers/tty/n_tty.c:2333
 do_tty_write drivers/tty/tty_io.c:959 [inline]
 tty_write+0x346/0x770 drivers/tty/tty_io.c:1043
 __vfs_write+0xdb/0x840 fs/read_write.c:480
 vfs_write+0x150/0x4f0 fs/read_write.c:544
 SYSC_write fs/read_write.c:590 [inline]
 SyS_write+0x100/0x250 fs/read_write.c:582
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c6c9
RSP: 002b:00007f0310adcc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f0310add6d4 RCX: 000000000045c6c9
RDX: 0000000000000078 RSI: 0000000020000140 RDI: 0000000000000004
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000ca8 R14: 00000000004ceba3 R15: 000000000076bf2c
==================================================================