bisecting fixing commit since 23ee3e4e5bd27bdbc0f1785eef7209ce872794c7 building syzkaller on 1f7cc1ca26f786658b146bf760d9698390e9bbfb testing commit 23ee3e4e5bd27bdbc0f1785eef7209ce872794c7 with gcc (GCC) 8.1.0 kernel signature: 1934ac818755f3d7ba9017b201a5af8760b85f8d47428001847a78476b2c40c8 run #0: crashed: BUG: unable to handle kernel NULL pointer dereference in rose_send_frame run #1: crashed: BUG: unable to handle kernel NULL pointer dereference in rose_send_frame run #2: crashed: BUG: unable to handle kernel NULL pointer dereference in rose_send_frame run #3: crashed: BUG: unable to handle kernel NULL pointer dereference in rose_send_frame run #4: crashed: BUG: unable to handle kernel NULL pointer dereference in rose_send_frame run #5: crashed: BUG: unable to handle kernel NULL pointer dereference in rose_send_frame run #6: crashed: BUG: unable to handle kernel NULL pointer dereference in rose_send_frame run #7: crashed: BUG: unable to handle kernel NULL pointer dereference in rose_send_frame run #8: crashed: BUG: unable to handle kernel NULL pointer dereference in rose_send_frame run #9: boot failed: can't ssh into the instance testing current HEAD 4d02da974ea85a62074efedf354e82778f910d82 testing commit 4d02da974ea85a62074efedf354e82778f910d82 with gcc (GCC) 8.1.0 kernel signature: c7fc0cc1e283c4a37765e93a455e63f90a5e65a64f930ac8c4a8d190c9761684 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in rose_send_frame revisions tested: 2, total time: 23m30.183778565s (build: 9m58.143830468s, test: 12m53.309317378s) the crash still happens on HEAD commit msg: Merge tag 'net-5.10-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net crash: BUG: unable to handle kernel NULL pointer dereference in rose_send_frame BUG: kernel NULL pointer dereference, address: 0000000000000360 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP CPU: 1 PID: 47 Comm: kworker/1:1 Not tainted 5.10.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: ipv6_addrconf addrconf_dad_work RIP: 0010:rose_send_frame+0x2c/0xc0 net/rose/rose_link.c:101 Code: 49 89 fc 48 c7 c7 20 26 a5 86 55 53 48 89 f3 48 c7 c6 a0 8b 99 83 e8 b3 39 00 00 4c 8b 4b 20 48 c7 c2 20 26 a5 86 85 c0 75 07 <49> 8b 91 60 03 00 00 48 8b 6b 18 48 8d 4b 08 be 04 01 00 00 4c 89 RSP: 0018:ffffc90000d08d68 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff8881068c1e00 RCX: 0000000000000000 RDX: ffffffff86a52620 RSI: ffffffff83998ba0 RDI: ffffffff86a52620 RBP: 0000000000000032 R08: 00000000000000c0 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000009 R12: ffff88810d2c6b00 R13: 0000000000000078 R14: 0000000000000005 R15: ffffffff82be03c0 FS: 0000000000000000(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000360 CR3: 000000011dbea000 CR4: 00000000001506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rose_transmit_clear_request+0x79/0xa0 net/rose/rose_link.c:255 rose_rx_call_request+0x172/0x630 net/rose/af_rose.c:998 rose_loopback_timer+0x81/0x150 net/rose/rose_loopback.c:100 call_timer_fn+0xa5/0x300 kernel/time/timer.c:1410 expire_timers kernel/time/timer.c:1455 [inline] __run_timers kernel/time/timer.c:1747 [inline] run_timer_softirq+0x20d/0x570 kernel/time/timer.c:1760 __do_softirq+0xe9/0x52f kernel/softirq.c:298 asm_call_irq_on_stack+0xf/0x20 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline] run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline] do_softirq_own_stack+0x7c/0xa0 arch/x86/kernel/irq_64.c:77 invoke_softirq kernel/softirq.c:393 [inline] __irq_exit_rcu kernel/softirq.c:423 [inline] irq_exit_rcu+0xea/0x110 kernel/softirq.c:435 sysvec_apic_timer_interrupt+0x57/0xf0 arch/x86/kernel/apic/apic.c:1091 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:631 RIP: 0010:mutex_spin_on_owner+0x5a/0x170 kernel/locking/mutex.c:556 Code: 48 c7 c7 40 89 3d 84 e8 a4 85 00 00 e8 7f 19 e9 01 59 85 c0 74 0d 80 3d 0e d0 4a 03 00 0f 84 b2 00 00 00 49 8b 06 48 83 e0 f8 <48> 39 c3 0f 85 02 01 00 00 8b 53 2c 85 d2 74 45 65 48 8b 04 25 c0 RSP: 0018:ffffc90000dcfce0 EFLAGS: 00000286 RAX: ffff888114d02100 RBX: ffff888114d02100 RCX: ffffffff8122c8b0 RDX: 0000000000000001 RSI: ffffffff84071d31 RDI: 0000000000000000 RBP: ffffc90000dcfd00 R08: 0000000000000003 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000010 R12: 0000000000000000 R13: 0000000000000000 R14: ffffffff84625960 R15: ffffffff82b0005f mutex_optimistic_spin kernel/locking/mutex.c:673 [inline] __mutex_lock_common kernel/locking/mutex.c:959 [inline] __mutex_lock+0x3d9/0x9f0 kernel/locking/mutex.c:1103 addrconf_dad_work+0x3f/0x500 net/ipv6/addrconf.c:4027 process_one_work+0x273/0x600 kernel/workqueue.c:2272 worker_thread+0x38/0x380 kernel/workqueue.c:2418 kthread+0x145/0x170 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Modules linked in: CR2: 0000000000000360 ---[ end trace 8e70568334ae6490 ]--- RIP: 0010:rose_send_frame+0x2c/0xc0 net/rose/rose_link.c:101 Code: 49 89 fc 48 c7 c7 20 26 a5 86 55 53 48 89 f3 48 c7 c6 a0 8b 99 83 e8 b3 39 00 00 4c 8b 4b 20 48 c7 c2 20 26 a5 86 85 c0 75 07 <49> 8b 91 60 03 00 00 48 8b 6b 18 48 8d 4b 08 be 04 01 00 00 4c 89 RSP: 0018:ffffc90000d08d68 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff8881068c1e00 RCX: 0000000000000000 RDX: ffffffff86a52620 RSI: ffffffff83998ba0 RDI: ffffffff86a52620 RBP: 0000000000000032 R08: 00000000000000c0 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000009 R12: ffff88810d2c6b00 R13: 0000000000000078 R14: 0000000000000005 R15: ffffffff82be03c0 FS: 0000000000000000(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000360 CR3: 000000011dbea000 CR4: 00000000001506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400