BUG: kernel NULL pointer dereference, address: 000000000000009c
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 10d29f067 P4D 10d29f067 PUD 10db2a067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP
CPU: 1 PID: 13582 Comm: syz-executor.0 Not tainted 5.10.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:kcsan_setup_watchpoint+0x215/0x4d0 kernel/kcsan/core.c:479
Code: 9d 4c 89 74 24 50 eb 05 ff 74 24 50 9d 48 83 c4 60 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f b7 08 89 ca c1 ea 08 31 db 31 f6 eb 26 <8b> 08 89 ca c1 ea 08 89 ce c1 ee 10 eb 18 48 8b 08 48 89 ca 48 c1
RSP: 0018:ffffc90003d1fc18 EFLAGS: 00010046
RAX: 000000000000009c RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: 00000000aaaaaaab R09: 000800000000009c
R10: 0000000000000246 R11: ffff8880155a5000 R12: 0000000000000004
R13: 0000000000000000 R14: ffff88801711a200 R15: 0000000000000001
FS:  00007f3218aa2700(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000009c CR3: 000000013b9c4000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 afs_unuse_cell+0x24/0x2b0 fs/afs/cell.c:592
 afs_cell_purge+0x72/0x1e0 fs/afs/cell.c:951
 afs_net_exit+0x67/0xa0 fs/afs/main.c:156
 ops_exit_list net/core/net_namespace.c:187 [inline]
 setup_net+0x397/0x630 net/core/net_namespace.c:365
 copy_net_ns+0x24f/0x390 net/core/net_namespace.c:483
 create_new_namespaces+0x231/0x540 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xe2/0x120 kernel/nsproxy.c:231
 ksys_unshare+0x38a/0x690 kernel/fork.c:2949
 __do_sys_unshare kernel/fork.c:3017 [inline]
 __se_sys_unshare kernel/fork.c:3015 [inline]
 __x64_sys_unshare+0x1b/0x20 kernel/fork.c:3015
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45deb9
Code: 0d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f3218aa1c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 0000000000038200 RCX: 000000000045deb9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000
RBP: 000000000118bf50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c
R13: 00007ffdd5149fbf R14: 00007f3218aa29c0 R15: 000000000118bf2c
Modules linked in:
CR2: 000000000000009c
---[ end trace e91d60230038daa3 ]---
RIP: 0010:kcsan_setup_watchpoint+0x215/0x4d0 kernel/kcsan/core.c:479
Code: 9d 4c 89 74 24 50 eb 05 ff 74 24 50 9d 48 83 c4 60 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f b7 08 89 ca c1 ea 08 31 db 31 f6 eb 26 <8b> 08 89 ca c1 ea 08 89 ce c1 ee 10 eb 18 48 8b 08 48 89 ca 48 c1
RSP: 0018:ffffc90003d1fc18 EFLAGS: 00010046
RAX: 000000000000009c RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: 00000000aaaaaaab R09: 000800000000009c
R10: 0000000000000246 R11: ffff8880155a5000 R12: 0000000000000004
R13: 0000000000000000 R14: ffff88801711a200 R15: 0000000000000001
FS:  00007f3218aa2700(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000009c CR3: 000000013b9c4000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400