bisecting cause commit starting from 6794862a16ef41f753abd75c03a152836e4c8028 building syzkaller on 5a5826a14e99564bdd4de163d3ac368056e5d992 testing commit 6794862a16ef41f753abd75c03a152836e4c8028 with gcc (GCC) 8.1.0 kernel signature: 9586713b6bc6b0236231280304c262694040ca88 all runs: crashed: KASAN: wild-memory-access Read in insert_char testing release v5.4 testing commit 219d54332a09e8d8741c1e1982f5eae56099de85 with gcc (GCC) 8.1.0 kernel signature: 1d6ffc1f924a18f262c382e2a99142812a1ee8c2 all runs: crashed: KASAN: wild-memory-access Read in insert_char testing release v5.3 testing commit 4d856f72c10ecb060868ed10ff1b1453943fc6c8 with gcc (GCC) 8.1.0 kernel signature: 9b2d5495e5345165d8f871dcbb1166fa52a5e946 all runs: crashed: KASAN: wild-memory-access Read in insert_char testing release v5.2 testing commit 0ecfebd2b52404ae0c54a878c872bb93363ada36 with gcc (GCC) 8.1.0 kernel signature: 617fca116cc16dbc16263610b42b81f42260d569 all runs: crashed: KASAN: wild-memory-access Read in insert_char testing release v5.1 testing commit e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd with gcc (GCC) 8.1.0 kernel signature: 12fa9cf75d747e207de4ff29be776dce7927c3eb all runs: crashed: KASAN: wild-memory-access Read in insert_char testing release v5.0 testing commit 1c163f4c7b3f621efff9b28a47abb36f7378d783 with gcc (GCC) 8.1.0 kernel signature: 071a21de15159792df312ff65603f66caa7515c6 all runs: crashed: KASAN: wild-memory-access Read in insert_char testing release v4.20 testing commit 8fe28cb58bcb235034b64cbbb7550a8a43fd88be with gcc (GCC) 8.1.0 kernel signature: a28f11b06a433b3c279096eaaf7b7fbc0b267d10 all runs: crashed: KASAN: wild-memory-access Read in insert_char testing release v4.19 testing commit 84df9525b0c27f3ebc2ebb1864fa62a97fdedb7d with gcc (GCC) 8.1.0 kernel signature: 65ccb6a99f38a7594117fc134aee150a63a0f559 all runs: crashed: KASAN: wild-memory-access Read in insert_char testing release v4.18 testing commit 94710cac0ef4ee177a63b5227664b38c95bbf703 with gcc (GCC) 8.1.0 kernel signature: f913ec56b83ac44ae6a192a34b2e0f742e910bb4 all runs: crashed: KASAN: wild-memory-access Read in insert_char testing release v4.17 testing commit 29dcea88779c856c7dc92040a0c01233263101d4 with gcc (GCC) 8.1.0 kernel signature: f0cbb9530f619b00b079b4609b2a11ebf47e2f93 all runs: crashed: KASAN: wild-memory-access Read in insert_char testing release v4.16 testing commit 0adb32858b0bddf4ada5f364a84ed60b196dbcda with gcc (GCC) 8.1.0 kernel signature: 5a1bb77bf73e78940c5649e028121fd97a05d856 all runs: crashed: KASAN: wild-memory-access Read in insert_char testing release v4.15 testing commit d8a5b80568a9cb66810e75b182018e9edb68e8ff with gcc (GCC) 8.1.0 kernel signature: 883d1dfe6070224134c98f1825305e8a9cb46b61 all runs: crashed: KASAN: wild-memory-access Read in insert_char testing release v4.14 testing commit bebc6082da0a9f5d47a1ea2edc099bf671058bd4 with gcc (GCC) 8.1.0 kernel signature: 11ee2058e1ee4be0df079891b43c8f1abda16c4a all runs: crashed: KASAN: wild-memory-access Read in insert_char testing release v4.13 testing commit 569dbb88e80deb68974ef6fdd6a13edb9d686261 with gcc (GCC) 8.1.0 kernel signature: b201d23bb5468fd2cc1d3912f7f1565903ecf038 all runs: crashed: general protection fault in insert_char testing release v4.12 testing commit 6f7da290413ba713f0cdd9ff1a2a9bb129ef4f6c with gcc (GCC) 8.1.0 kernel signature: 744ccafc4e36dd5b3764ce778fdb1756a1931888 all runs: crashed: general protection fault in insert_char testing release v4.11 testing commit a351e9b9fc24e982ec2f0e76379a49826036da12 with gcc (GCC) 7.3.0 kernel signature: c8d07127fd2d147758930d801888d693fdfe5b87 all runs: crashed: general protection fault in insert_char testing release v4.10 testing commit c470abd4fde40ea6a0846a2beab642a578c0b8cd with gcc (GCC) 5.5.0 kernel signature: d22c0c23e04b3bfc61290c9a4ebbe728918678df all runs: crashed: general protection fault in insert_char testing release v4.9 testing commit 69973b830859bc6529a7a0468ba0d80ee5117826 with gcc (GCC) 5.5.0 kernel signature: 0b2b3ce837a8a083194362d664153f924076a28c all runs: crashed: general protection fault in insert_char testing release v4.8 testing commit c8d2bc9bc39ebea8437fd974fdbc21847bb897a3 with gcc (GCC) 5.5.0 kernel signature: 1cda2dd5c2c509df97368cf6dd6c0ef69a827318 all runs: crashed: general protection fault in insert_char testing release v4.7 testing commit 523d939ef98fd712632d93a5a2b588e477a7565e with gcc (GCC) 5.5.0 kernel signature: 3e23dc8fbfae329a774ee68725d7e7710bc0fdf8 all runs: crashed: general protection fault in insert_char testing release v4.6 testing commit 2dcd0af568b0cf583645c8a317dd12e344b1c72a with gcc (GCC) 5.5.0 kernel signature: c359c307c7419bef84522a79088f952adca5bb9d run #0: crashed: general protection fault in insert_char run #1: crashed: general protection fault in insert_char run #2: crashed: general protection fault in insert_char run #3: crashed: general protection fault in skb_dequeue run #4: crashed: general protection fault in insert_char run #5: crashed: general protection fault in __inet_insert_ifa run #6: crashed: general protection fault in insert_char run #7: crashed: general protection fault in insert_char run #8: crashed: general protection fault in insert_char run #9: crashed: general protection fault in insert_char revisions tested: 21, total time: 3h1m32.402093016s (build: 1h49m40.634727884s, test: 1h9m13.641188423s) the crash already happened on the oldest tested release commit msg: Linux 4.6 crash: general protection fault in insert_char IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_0: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN Modules linked in: CPU: 0 PID: 7318 Comm: syz-executor.5 Not tainted 4.6.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8800b6182700 ti: ffff8800ae408000 task.ti: ffff8800ae408000 RIP: 0010:[] [] scr_memmovew include/linux/vt_buffer.h:54 [inline] RIP: 0010:[] [] insert_char+0x28a/0x420 drivers/tty/vt/vt.c:550 RSP: 0018:ffff8800ae40f6e8 EFLAGS: 00010203 RAX: 0000000020000001 RBX: 000000010000000e RCX: dffffc0000000000 RDX: 00000000000000d2 RSI: 0000000000000001 RDI: ffff8800aec663b4 RBP: ffff8800ae40f738 R08: 00000000ffffff3c R09: dffffc0000000000 R10: 0000000000000011 R11: 0000000000000001 R12: 00000000ffffff3a R13: 000000010000000c R14: ffff8800aec66040 R15: 00000000ffffff3a FS: 0000000000000000(0000) GS:ffff88012c000000(0063) knlGS:00000000f7770b40 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 0000000008178090 CR3: 00000000ae48b000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: ffff8800b6182f00 ffff8800b6182f08 ffff8800b6182fd0 1ffff10015c81ee2 ffff880000000000 000000000000006b ffff8800aec66040 0000000000000000 ffffed0015d8cc7f 1ffff10015c81ef0 ffff8800ae40f8a8 ffffffff82fdbdae Call Trace: [] csi_at drivers/tty/vt/vt.c:1616 [inline] [] do_con_trol+0x504e/0x5a40 drivers/tty/vt/vt.c:2063 [] do_con_write.part.22+0x487/0x1950 drivers/tty/vt/vt.c:2421 [] do_con_write drivers/tty/vt/vt.c:2779 [inline] [] con_write+0x76/0x90 drivers/tty/vt/vt.c:2775 [] process_output_block drivers/tty/n_tty.c:581 [inline] [] n_tty_write+0x4f0/0x10b0 drivers/tty/n_tty.c:2313 [] do_tty_write drivers/tty/tty_io.c:1175 [inline] [] tty_write+0x44d/0x7f0 drivers/tty/tty_io.c:1260 [] __vfs_write+0xdb/0x4f0 fs/read_write.c:529 [] vfs_write+0x13a/0x4a0 fs/read_write.c:578 [] SYSC_write fs/read_write.c:625 [inline] [] SyS_write+0xcb/0x1a0 fs/read_write.c:617 [] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline] [] do_fast_syscall_32+0x324/0xa70 arch/x86/entry/common.c:454 [] entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:125 Code: 84 dd fe ff ff 48 b9 00 00 00 00 00 fc ff df 48 01 d2 48 89 d8 48 29 d0 4c 8d 40 fe 49 83 ed 02 48 83 eb 02 4c 89 e8 48 c1 e8 03 <0f> b6 14 08 4c 89 e8 83 e0 07 83 c0 01 38 d0 7c 08 84 d2 0f 85 RIP [] scr_memmovew include/linux/vt_buffer.h:54 [inline] RIP [] insert_char+0x28a/0x420 drivers/tty/vt/vt.c:550 RSP ---[ end trace c7f306e0c4c57dde ]---