Re: [syzbot] BUG: unable to handle kernel NULL pointer dereference in __rxe_do_task

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    05a5474efe93 Merge git://git.kernel.org/pub/scm/linux/kern..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=14e4bddb080000
kernel config:  https://syzkaller.appspot.com/x/.config?x=892a57667b7af6cf
dashboard link: https://syzkaller.appspot.com/bug?extid=ab99dc4c6e961eed8b8e
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17718427080000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/cdeb0ae7599a/disk-05a5474e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d59d928441e6/vmlinux-05a5474e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ab99dc4c6e961eed8b8e@xxxxxxxxxxxxxxxxxxxxxxxxx

infiniband syz0: set active
infiniband syz0: added ip6gre0
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 1d64c067 P4D 1d64c067 PUD 22925067 PMD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 3780 Comm: syz-executor.1 Not tainted 6.0.0-rc3-syzkaller-00123-g05a5474efe93 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc9000413eb40 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8880776e25c8 RCX: 0000000000000000
RDX: ffff88807932bb00 RSI: ffffffff86d530bb RDI: 0000000000000000
RBP: ffffed100eedc4c8 R08: 0000000000000001 R09: ffff8880776e269f
R10: ffffed100eedc4d3 R11: 0000000000000000 R12: 0000000000000000
R13: ffffed100eedc4c9 R14: ffff8880776e2640 R15: ffff8880776e2648
FS:  00007f1d65587700(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000001bd9d000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __rxe_do_task+0x56/0xc0 drivers/infiniband/sw/rxe/rxe_task.c:18
 rxe_qp_do_cleanup+0x102/0x770 drivers/infiniband/sw/rxe/rxe_qp.c:800
 execute_in_process_context+0x37/0x150 kernel/workqueue.c:3359
 __rxe_cleanup+0x21a/0x400 drivers/infiniband/sw/rxe/rxe_pool.c:276
 rxe_create_qp+0x2be/0x340 drivers/infiniband/sw/rxe/rxe_verbs.c:441
 create_qp+0x5ac/0x960 drivers/infiniband/core/verbs.c:1233
 ib_create_qp_kernel+0x9d/0x310 drivers/infiniband/core/verbs.c:1344
 ib_create_qp include/rdma/ib_verbs.h:3732 [inline]
 create_mad_qp+0x177/0x2d0 drivers/infiniband/core/mad.c:2910
 ib_mad_port_open drivers/infiniband/core/mad.c:2991 [inline]
 ib_mad_init_device+0xd51/0x13f0 drivers/infiniband/core/mad.c:3082
 add_client_context+0x405/0x5e0 drivers/infiniband/core/device.c:721
 enable_device_and_get+0x1cd/0x3b0 drivers/infiniband/core/device.c:1332
 ib_register_device drivers/infiniband/core/device.c:1420 [inline]
 ib_register_device+0x83e/0xb20 drivers/infiniband/core/device.c:1366
 rxe_register_device+0x2fe/0x3b0 drivers/infiniband/sw/rxe/rxe_verbs.c:1138
 rxe_net_add+0x8c/0xe0 drivers/infiniband/sw/rxe/rxe_net.c:521
 rxe_newlink drivers/infiniband/sw/rxe/rxe.c:195 [inline]
 rxe_newlink+0xa9/0xd0 drivers/infiniband/sw/rxe/rxe.c:176
 nldev_newlink+0x32e/0x5c0 drivers/infiniband/core/nldev.c:1717
 rdma_nl_rcv_msg+0x36d/0x690 drivers/infiniband/core/netlink.c:195
 rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline]
 rdma_nl_rcv+0x2ee/0x430 drivers/infiniband/core/netlink.c:259
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x543/0x7f0 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x917/0xe10 net/netlink/af_netlink.c:1921
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:734
 ____sys_sendmsg+0x6eb/0x810 net/socket.c:2482
 ___sys_sendmsg+0x110/0x1b0 net/socket.c:2536
 __sys_sendmsg+0xf3/0x1c0 net/socket.c:2565
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f1d64489279
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1d65587168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f1d6459bf80 RCX: 00007f1d64489279
RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000003
RBP: 00007f1d644e32e9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd40d1b80f R14: 00007f1d65587300 R15: 0000000000022000
 </TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc9000413eb40 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8880776e25c8 RCX: 0000000000000000
RDX: ffff88807932bb00 RSI: ffffffff86d530bb RDI: 0000000000000000
RBP: ffffed100eedc4c8 R08: 0000000000000001 R09: ffff8880776e269f
R10: ffffed100eedc4d3 R11: 0000000000000000 R12: 0000000000000000
R13: ffffed100eedc4c9 R14: ffff8880776e2640 R15: ffff8880776e2648
FS:  00007f1d65587700(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000001bd9d000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400