bisecting cause commit starting from 1c163f4c7b3f621efff9b28a47abb36f7378d783 building syzkaller on 1c0e457aaaae0f885242810950c8a7c3508eabbb testing commit 1c163f4c7b3f621efff9b28a47abb36f7378d783 with gcc (GCC) 8.1.0 run #0: crashed: general protection fault in rose_send_frame run #1: crashed: general protection fault in rose_send_frame run #2: crashed: general protection fault in rose_send_frame run #3: crashed: general protection fault in rose_send_frame run #4: crashed: general protection fault in rose_send_frame run #5: OK run #6: OK run #7: OK run #8: OK run #9: OK testing release v4.20 testing commit 8fe28cb58bcb235034b64cbbb7550a8a43fd88be with gcc (GCC) 8.1.0 run #0: crashed: general protection fault in ax25cmp run #1: crashed: general protection fault in ax25cmp run #2: crashed: general protection fault in ax25cmp run #3: crashed: general protection fault in ax25cmp run #4: crashed: general protection fault in ax25cmp run #5: crashed: general protection fault in corrupted run #6: crashed: general protection fault in ax25cmp run #7: crashed: general protection fault in ax25cmp run #8: crashed: general protection fault in ax25cmp run #9: crashed: general protection fault in ax25cmp testing release v4.19 testing commit 84df9525b0c27f3ebc2ebb1864fa62a97fdedb7d with gcc (GCC) 8.1.0 all runs: crashed: general protection fault in ax25cmp testing release v4.18 testing commit 94710cac0ef4ee177a63b5227664b38c95bbf703 with gcc (GCC) 8.1.0 all runs: crashed: general protection fault in ax25cmp testing release v4.17 testing commit 29dcea88779c856c7dc92040a0c01233263101d4 with gcc (GCC) 8.1.0 run #0: crashed: general protection fault in ax25cmp run #1: crashed: general protection fault in rose_send_frame run #2: crashed: general protection fault in rose_send_frame run #3: crashed: general protection fault in ax25cmp run #4: crashed: general protection fault in ax25cmp run #5: crashed: general protection fault in ax25cmp run #6: crashed: general protection fault in ax25cmp run #7: crashed: general protection fault in ax25cmp run #8: crashed: general protection fault in ax25cmp run #9: crashed: general protection fault in ax25cmp testing release v4.16 testing commit 0adb32858b0bddf4ada5f364a84ed60b196dbcda with gcc (GCC) 8.1.0 all runs: crashed: general protection fault in ax25cmp testing release v4.15 testing commit d8a5b80568a9cb66810e75b182018e9edb68e8ff with gcc (GCC) 8.1.0 all runs: crashed: general protection fault in ax25cmp testing release v4.14 testing commit bebc6082da0a9f5d47a1ea2edc099bf671058bd4 with gcc (GCC) 8.1.0 all runs: crashed: general protection fault in ax25cmp testing release v4.13 testing commit 569dbb88e80deb68974ef6fdd6a13edb9d686261 with gcc (GCC) 8.1.0 all runs: crashed: general protection fault in ax25cmp testing release v4.12 testing commit 6f7da290413ba713f0cdd9ff1a2a9bb129ef4f6c with gcc (GCC) 8.1.0 all runs: crashed: general protection fault in ax25cmp testing release v4.11 testing commit a351e9b9fc24e982ec2f0e76379a49826036da12 with gcc (GCC) 7.3.0 all runs: crashed: general protection fault in ax25cmp testing release v4.10 testing commit c470abd4fde40ea6a0846a2beab642a578c0b8cd with gcc (GCC) 5.5.0 run #0: crashed: general protection fault in rose_send_frame run #1: crashed: general protection fault in ax25cmp run #2: crashed: general protection fault in ax25cmp run #3: crashed: general protection fault in ax25cmp run #4: crashed: general protection fault in rose_send_frame run #5: crashed: general protection fault in ax25cmp run #6: crashed: general protection fault in rose_send_frame run #7: crashed: general protection fault in rose_send_frame run #8: crashed: general protection fault in rose_send_frame run #9: crashed: general protection fault in ax25cmp testing release v4.9 testing commit 69973b830859bc6529a7a0468ba0d80ee5117826 with gcc (GCC) 5.5.0 all runs: crashed: general protection fault in ax25cmp testing release v4.8 testing commit c8d2bc9bc39ebea8437fd974fdbc21847bb897a3 with gcc (GCC) 5.5.0 run #0: crashed: general protection fault in ax25cmp run #1: crashed: general protection fault in rose_send_frame run #2: crashed: general protection fault in ax25cmp run #3: crashed: general protection fault in ax25cmp run #4: crashed: general protection fault in ax25cmp run #5: crashed: general protection fault in ax25cmp run #6: crashed: general protection fault in ax25cmp run #7: crashed: general protection fault in ax25cmp run #8: crashed: general protection fault in ax25cmp run #9: crashed: general protection fault in ax25cmp testing release v4.7 testing commit 523d939ef98fd712632d93a5a2b588e477a7565e with gcc (GCC) 5.5.0 all runs: crashed: general protection fault in ax25cmp testing release v4.6 testing commit 2dcd0af568b0cf583645c8a317dd12e344b1c72a with gcc (GCC) 5.5.0 all runs: crashed: general protection fault in ax25cmp testing release v4.5 testing commit b562e44f507e863c6792946e4e1b1449fbbac85d with gcc (GCC) 5.5.0 crypto/rsa_helper.c:18:28: fatal error: rsapubkey-asn1.h: No such file or directory testing release v4.4 testing commit afd2ff9b7e1b367172f18ba7f693dfb62bdcb2dc with gcc (GCC) 5.5.0 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in ax25cmp testing release v4.3 testing commit 6a13feb9c82803e2b815eca72fa7a9f5561d7861 with gcc (GCC) 5.5.0 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in ax25cmp testing release v4.2 testing commit 64291f7db5bd8150a74ad2036f1037e6a0428df2 with gcc (GCC) 5.5.0 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in ax25cmp testing release v4.1 testing commit b953c0d234bc72e8489d3bf51a276c5c4ec85345 with gcc (GCC) 5.5.0 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in ax25cmp revisions tested: 21, total time: 2h36m6.350238628s (build: 1h19m46.9657135s, test: 1h12m20.413303971s) the crash already happened on the oldest tested release crash: BUG: unable to handle kernel NULL pointer dereference in ax25cmp bridge0: port 2(bridge_slave_1) entered forwarding state bridge0: port 1(bridge_slave_0) entered forwarding state bridge0: port 2(bridge_slave_1) entered forwarding state bridge0: port 1(bridge_slave_0) entered forwarding state bridge0: port 2(bridge_slave_1) entered forwarding state BUG: unable to handle kernel NULL pointer dereference at 0000000000000017 IP: [] ax25cmp+0x6/0x40 net/ax25/ax25_addr.c:122 PGD 0 Oops: 0000 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 2251 Comm: aoe_tx0 Not tainted 4.1.0 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 task: ffff88003d8b4910 ti: ffff88003d49c000 task.ti: ffff88003d49c000 RIP: 0010:[] [] ax25cmp+0x6/0x40 net/ax25/ax25_addr.c:122 RSP: 0018:ffff88003d49fb98 EFLAGS: 00010246 RAX: ffff88003d8b4910 RBX: 0000000000000017 RCX: 0000000000000200 RDX: 0000000000000000 RSI: ffff88003b18e808 RDI: 0000000000000017 RBP: ffff88003d49fb98 R08: ffffffff83dde1a0 R09: 0000000000000000 R10: 0000000000007db2 R11: ffffffff836691e0 R12: 0000000000000000 R13: ffff88003b18e800 R14: ffff88003b703cb0 R15: 00000000000000ff FS: 0000000000000000(0000) GS:ffff88003ec00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000017 CR3: 000000000320d000 CR4: 00000000003407f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: ffff88003d49fc88 ffffffff823769cc ffff880036008000 00000000000005ff 00000000000000ff 000000000046a5ff 0000000000000000 000000000046a505 ffff88003d49fca8 ffffffff811c626f 0000000000000000 ffffffff83ddde80 Call Trace: [] rose_route_frame+0x9c/0x680 net/rose/rose_route.c:884 [] rose_xmit+0x29/0x90 net/rose/rose_dev.c:110 [] __netdev_start_xmit include/linux/netdevice.h:3610 [inline] [] netdev_start_xmit include/linux/netdevice.h:3619 [inline] [] xmit_one net/core/dev.c:2654 [inline] [] dev_hard_start_xmit+0x2fd/0x7f0 net/core/dev.c:2670 [] __dev_queue_xmit+0x88d/0x950 net/core/dev.c:2997 [] dev_queue_xmit_sk+0xe/0x10 net/core/dev.c:3031 [] dev_queue_xmit include/linux/netdevice.h:2178 [inline] [] tx+0x5c/0xa0 drivers/block/aoe/aoenet.c:63 [] kthread+0x9c/0x100 drivers/block/aoe/aoecmd.c:1300 [] kthread+0xea/0x100 drivers/block/aoe/aoecmd.c:1312 [] ret_from_fork+0x42/0x70 arch/x86/kernel/entry_64.S:639 Code: 31 83 c0 30 c6 42 01 00 88 02 0f b6 07 84 c0 75 d7 48 c7 c0 e1 4e f7 82 5d c3 90 66 2e 0f 1f 84 00 00 00 00 00 55 31 d2 48 89 e5 <0f> b6 04 17 32 04 16 25 fe 00 00 00 75 24 48 83 c2 01 48 83 fa RIP [] ax25cmp+0x6/0x40 net/ax25/ax25_addr.c:118 RSP CR2: 0000000000000017 ---[ end trace 51e23711b5313921 ]---