bisecting fixing commit since d15be546031cf65a0fc34879beca02fd90fe7ac7 building syzkaller on 70c104a18f3d409bc6dde950b50258d3d280d99b testing commit d15be546031cf65a0fc34879beca02fd90fe7ac7 with gcc (GCC) 8.1.0 kernel signature: d40497c3bc201c5f11f05a281ae3cbd435ef2d1707cdd10e7822e3b0b2a8cec5 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in rose_send_frame testing current HEAD c2dc4c073fb71b50904493657a7622b481b346e3 testing commit c2dc4c073fb71b50904493657a7622b481b346e3 with gcc (GCC) 8.1.0 kernel signature: e3f94ee2e9570a898fc2fa4f4c5703dc5dc5434cb74f03d3a3c01f69e9983008 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in rose_send_frame revisions tested: 2, total time: 16m32.603302467s (build: 10m18.885035444s, test: 5m36.793818429s) the crash still happens on HEAD commit msg: Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost 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 101de3067 P4D 101de3067 PUD 10b6a1067 PMD 0 Oops: 0000 [#1] PREEMPT SMP CPU: 0 PID: 6990 Comm: syz-executor.2 Not tainted 5.10.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:rose_send_frame+0x2c/0xc0 net/rose/rose_link.c:101 Code: 49 89 fc 48 c7 c7 60 26 a5 86 55 53 48 89 f3 48 c7 c6 e0 6a 99 83 e8 b3 39 00 00 4c 8b 4b 20 48 c7 c2 60 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:ffffc90000003d68 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff888106b10600 RCX: 0000000000000000 RDX: ffffffff86a52660 RSI: ffffffff83996ae0 RDI: ffffffff86a52660 RBP: 0000000000000032 R08: 00000000000000c0 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000009 R12: ffff88810b671600 R13: 0000000000000078 R14: 0000000000000005 R15: ffffffff82bda400 FS: 0000000002987940(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000360 CR3: 000000010b6c1000 CR4: 00000000001506f0 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:1415 expire_timers kernel/time/timer.c:1460 [inline] __run_timers kernel/time/timer.c:1752 [inline] run_timer_softirq+0x20d/0x570 kernel/time/timer.c:1765 __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 do_softirq.part.16+0x98/0xc0 kernel/softirq.c:343 do_softirq kernel/softirq.c:335 [inline] __local_bh_enable_ip+0x142/0x150 kernel/softirq.c:195 inet6_addr_add+0x18e/0x270 net/ipv6/addrconf.c:2964 inet6_rtm_newaddr+0x4a2/0x680 net/ipv6/addrconf.c:4865 rtnetlink_rcv_msg+0x173/0x480 net/core/rtnetlink.c:5562 netlink_rcv_skb+0x49/0xf0 net/netlink/af_netlink.c:2494 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline] netlink_unicast+0x19a/0x270 net/netlink/af_netlink.c:1330 netlink_sendmsg+0x248/0x480 net/netlink/af_netlink.c:1919 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0x2b/0x40 net/socket.c:671 __sys_sendto+0xec/0x160 net/socket.c:1992 __do_sys_sendto net/socket.c:2004 [inline] __se_sys_sendto net/socket.c:2000 [inline] __x64_sys_sendto+0x1f/0x30 net/socket.c:2000 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x415ed3 Code: ff 0f 83 b0 19 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 83 3d bd 3a 89 00 00 75 17 49 89 ca b8 2c 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 81 19 00 00 c3 48 83 ec 08 e8 87 fa ff ff RSP: 002b:00007ffcca08d958 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000000ca3700 RCX: 0000000000415ed3 RDX: 0000000000000040 RSI: 0000000000ca3750 RDI: 0000000000000003 RBP: 0000000000000000 R08: 00007ffcca08d960 R09: 000000000000000c R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000ca3750 R15: 0000000000000003 Modules linked in: CR2: 0000000000000360 ---[ end trace 973fcd0f1b9539b7 ]--- RIP: 0010:rose_send_frame+0x2c/0xc0 net/rose/rose_link.c:101 Code: 49 89 fc 48 c7 c7 60 26 a5 86 55 53 48 89 f3 48 c7 c6 e0 6a 99 83 e8 b3 39 00 00 4c 8b 4b 20 48 c7 c2 60 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:ffffc90000003d68 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff888106b10600 RCX: 0000000000000000 RDX: ffffffff86a52660 RSI: ffffffff83996ae0 RDI: ffffffff86a52660 RBP: 0000000000000032 R08: 00000000000000c0 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000009 R12: ffff88810b671600 R13: 0000000000000078 R14: 0000000000000005 R15: ffffffff82bda400 FS: 0000000002987940(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000360 CR3: 000000010b6c1000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400