bisecting cause commit starting from 6794862a16ef41f753abd75c03a152836e4c8028 building syzkaller on 5a5826a14e99564bdd4de163d3ac368056e5d992 testing commit 6794862a16ef41f753abd75c03a152836e4c8028 with gcc (GCC) 8.1.0 kernel signature: ed55cc037597553ed505ac495b4098c1275018f7 all runs: crashed: KASAN: user-memory-access Read in insert_char testing release v5.4 testing commit 219d54332a09e8d8741c1e1982f5eae56099de85 with gcc (GCC) 8.1.0 kernel signature: 5d93b2146a77548f9e95fef0ffbe7238105ab74a all runs: crashed: KASAN: user-memory-access Read in insert_char testing release v5.3 testing commit 4d856f72c10ecb060868ed10ff1b1453943fc6c8 with gcc (GCC) 8.1.0 kernel signature: d54fb9fe527ee78fef1ffd442a32eae2ff4064b4 all runs: crashed: KASAN: user-memory-access Read in insert_char testing release v5.2 testing commit 0ecfebd2b52404ae0c54a878c872bb93363ada36 with gcc (GCC) 8.1.0 kernel signature: 93ea5a088a730b1a2cf04466f1237ad3d83d2c65 all runs: crashed: KASAN: user-memory-access Read in insert_char testing release v5.1 testing commit e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd with gcc (GCC) 8.1.0 kernel signature: 13280f80ac1e6a89f44fcc11f656c8999bbe0544 all runs: crashed: KASAN: user-memory-access Read in insert_char testing release v5.0 testing commit 1c163f4c7b3f621efff9b28a47abb36f7378d783 with gcc (GCC) 8.1.0 kernel signature: 1445adf790ad06f491e4c6fefb0b3ff69316223c run #0: basic kernel testing failed: failed to copy test binary to VM: failed to run ["scp" "-P" "22" "-F" "/dev/null" "-o" "UserKnownHostsFile=/dev/null" "-o" "BatchMode=yes" "-o" "IdentitiesOnly=yes" "-o" "StrictHostKeyChecking=no" "-o" "ConnectTimeout=10" "-i" "/syzkaller/jobs/linux/workdir/image/key" "/syzkaller/jobs/linux/workdir/repro.prog" "root@10.128.15.205:./repro.prog"]: exit status 1 Warning: Permanently added '10.128.15.205' (ECDSA) to the list of known hosts. /syzkaller/jobs/linux/workdir/repro.prog: Broken pipe run #1: crashed: KASAN: user-memory-access Read in insert_char run #2: crashed: KASAN: user-memory-access Read in insert_char run #3: crashed: KASAN: user-memory-access Read in insert_char run #4: crashed: KASAN: user-memory-access Read in insert_char run #5: crashed: KASAN: user-memory-access Read in insert_char run #6: crashed: KASAN: user-memory-access Read in insert_char run #7: crashed: KASAN: user-memory-access Read in insert_char run #8: crashed: KASAN: user-memory-access Read in insert_char run #9: crashed: KASAN: user-memory-access Read in insert_char testing release v4.20 testing commit 8fe28cb58bcb235034b64cbbb7550a8a43fd88be with gcc (GCC) 8.1.0 kernel signature: a710d450612b301156ba9b0803610d071c3b51d6 all runs: crashed: KASAN: user-memory-access Read in insert_char testing release v4.19 testing commit 84df9525b0c27f3ebc2ebb1864fa62a97fdedb7d with gcc (GCC) 8.1.0 kernel signature: d0a674afa9ba1431ecc87ea6787c82a45a4915bb all runs: crashed: KASAN: user-memory-access Read in insert_char testing release v4.18 testing commit 94710cac0ef4ee177a63b5227664b38c95bbf703 with gcc (GCC) 8.1.0 kernel signature: 3f6d9a7bd36540cf1ba81f404de9cf730b1a50d4 all runs: crashed: KASAN: user-memory-access Read in insert_char testing release v4.17 testing commit 29dcea88779c856c7dc92040a0c01233263101d4 with gcc (GCC) 8.1.0 kernel signature: 40eed7ef60a1d5a8b358390410779dd17ac70c03 all runs: crashed: KASAN: user-memory-access Read in insert_char testing release v4.16 testing commit 0adb32858b0bddf4ada5f364a84ed60b196dbcda with gcc (GCC) 8.1.0 kernel signature: 1ba86f02dc317fa4cf95530613ba9138215a997c all runs: crashed: KASAN: user-memory-access Read in insert_char testing release v4.15 testing commit d8a5b80568a9cb66810e75b182018e9edb68e8ff with gcc (GCC) 8.1.0 kernel signature: 160fe29c10f48cdee453f5a32fc6e32d299b49db all runs: crashed: KASAN: user-memory-access Read in insert_char testing release v4.14 testing commit bebc6082da0a9f5d47a1ea2edc099bf671058bd4 with gcc (GCC) 8.1.0 kernel signature: bb1c679f5740f7f94a5bc1bc01d11838893d69cc all runs: crashed: KASAN: user-memory-access Read in insert_char testing release v4.13 testing commit 569dbb88e80deb68974ef6fdd6a13edb9d686261 with gcc (GCC) 8.1.0 kernel signature: 71a419c6706e17771b72582f38ab5161ed5fe651 all runs: crashed: general protection fault in insert_char testing release v4.12 testing commit 6f7da290413ba713f0cdd9ff1a2a9bb129ef4f6c with gcc (GCC) 8.1.0 kernel signature: f64d2f0b22cbbb814c75e3ca595b19d61d3ec8fe all runs: crashed: general protection fault in insert_char testing release v4.11 testing commit a351e9b9fc24e982ec2f0e76379a49826036da12 with gcc (GCC) 7.3.0 kernel signature: 36e110a02978a94ef8e43f14ce6212a1b35b3dff all runs: crashed: general protection fault in insert_char testing release v4.10 testing commit c470abd4fde40ea6a0846a2beab642a578c0b8cd with gcc (GCC) 5.5.0 kernel signature: eab38807ea088e28d25b68040e66c60cd9d8e3b1 all runs: crashed: general protection fault in insert_char testing release v4.9 testing commit 69973b830859bc6529a7a0468ba0d80ee5117826 with gcc (GCC) 5.5.0 kernel signature: f7a5d198dd5cbe1d2d268ef65bdc6ce084a1ad71 all runs: crashed: general protection fault in insert_char testing release v4.8 testing commit c8d2bc9bc39ebea8437fd974fdbc21847bb897a3 with gcc (GCC) 5.5.0 kernel signature: 0f22fb6f93c1af26caf1c8fe9571124311f26bff all runs: crashed: general protection fault in insert_char testing release v4.7 testing commit 523d939ef98fd712632d93a5a2b588e477a7565e with gcc (GCC) 5.5.0 kernel signature: 46744e597cbe3c15334ceddf73d658ba56762171 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 netprio_prio run #3: crashed: general protection fault in insert_char run #4: crashed: general protection fault in insert_char run #5: crashed: WARNING in rcu_process_callbacks 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 mm_update_next_owner testing release v4.6 testing commit 2dcd0af568b0cf583645c8a317dd12e344b1c72a with gcc (GCC) 5.5.0 kernel signature: e164deab9b6bdff3e638be721f14ced7cb953395 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 insert_char run #4: crashed: general protection fault in insert_char run #5: crashed: general protection fault in insert_char run #6: crashed: general protection fault in insert_char run #7: crashed: general protection fault in insert_char run #8: crashed: INFO: trying to register non-static key in batadv_tt_local_purge run #9: crashed: general protection fault in insert_char revisions tested: 21, total time: 3h5m3.409513203s (build: 1h53m22.50286264s, test: 1h9m11.874661274s) 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: 7266 Comm: syz-executor.4 Not tainted 4.6.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8800b79ec440 ti: ffff880129b60000 task.ti: ffff880129b60000 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:ffff880129b67768 EFLAGS: 00010203 RAX: 0000000020000001 RBX: 000000010000000e RCX: dffffc0000000000 RDX: 00000000000000d2 RSI: 0000000000000001 RDI: ffff8800af4ae6f4 RBP: ffff880129b677b8 R08: 00000000ffffff3c R09: dffffc0000000000 R10: 0000000000000011 R11: 0000000000000001 R12: 00000000ffffff3a R13: 000000010000000c R14: ffff8800af4ae380 R15: 00000000ffffff3a FS: 00007f998e1a0700(0000) GS:ffff88012c000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000758090 CR3: 00000000af651000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: ffff8800b79ecc40 ffff8800b79ecc48 ffff8800b79ecd10 1ffff1002536cef2 ffff880000000000 000000000000006b ffff8800af4ae380 0000000000000000 ffffed0015e95ce7 1ffff1002536cf00 ffff880129b67928 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 [] entry_SYSCALL_64_fastpath+0x23/0xc1 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 51a5821d957ab742 ]---