BUG: kernel NULL pointer dereference, address: 0000000000000080
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 84bfd067 P4D 84bfd067 PUD 84bfe067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 32764 Comm: syz-executor.0 Not tainted 5.1.0+ #15
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:slab_equal_or_root mm/slab.h:229 [inline]
RIP: 0010:cache_from_obj mm/slab.h:371 [inline]
RIP: 0010:cache_from_obj mm/slab.h:353 [inline]
RIP: 0010:kmem_cache_free+0x207/0x260 mm/slab.c:3720
Code: ea ff ff 48 c1 e8 0c 48 c1 e0 06 48 01 d0 48 8b 50 08 48 8d 4a ff 83 e2 01 48 0f 45 c1 48 8b 40 18 49 39 c4 0f 84 19 fe ff ff <4c> 3b a0 80 00 00 00 0f 85 60 1e 00 00 49 89 c4 e9 04 fe ff ff 0f
RSP: 0018:ffff88809119fd08 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff8880a8970900 RCX: ffffea0001611107
RDX: 0000000000000000 RSI: ffffffff8132f254 RDI: 0000000000000007
RBP: ffff88809119fd28 R08: ffff888095aec580 R09: 0000000000000001
R10: ffffed1015d06bdf R11: ffff8880ae835efb R12: ffff8880aa587600
R13: ffff888095aecc68 R14: ffff888095aecd08 R15: ffff8880a8970908
FS:  0000000000ad5940(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000080 CR3: 0000000084bfc000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 free_fs_struct+0x4f/0x70 fs/fs_struct.c:91
 exit_fs+0xf0/0x130 fs/fs_struct.c:107
 do_exit+0x8e0/0x2fa0 kernel/exit.c:872
 do_group_exit+0x135/0x370 kernel/exit.c:980
 __do_sys_exit_group kernel/exit.c:991 [inline]
 __se_sys_exit_group kernel/exit.c:989 [inline]
 __x64_sys_exit_group+0x44/0x50 kernel/exit.c:989
 do_syscall_64+0x103/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458da9
Code: ad b8 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 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc4e572698 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000000000000001e RCX: 0000000000458da9
RDX: 0000000000412b61 RSI: fffffffffffffff7 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffffffffffff R09: 00007ffc4e5726f0
R10: 00007fd058f6a700 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffc4e5726f0 R14: 0000000000000000 R15: 00007ffc4e572700
Modules linked in:
CR2: 0000000000000080
---[ end trace b4a9f0914478fae6 ]---
RIP: 0010:slab_equal_or_root mm/slab.h:229 [inline]
RIP: 0010:cache_from_obj mm/slab.h:371 [inline]
RIP: 0010:cache_from_obj mm/slab.h:353 [inline]
RIP: 0010:kmem_cache_free+0x207/0x260 mm/slab.c:3720
Code: ea ff ff 48 c1 e8 0c 48 c1 e0 06 48 01 d0 48 8b 50 08 48 8d 4a ff 83 e2 01 48 0f 45 c1 48 8b 40 18 49 39 c4 0f 84 19 fe ff ff <4c> 3b a0 80 00 00 00 0f 85 60 1e 00 00 49 89 c4 e9 04 fe ff ff 0f
RSP: 0018:ffff88809119fd08 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff8880a8970900 RCX: ffffea0001611107
RDX: 0000000000000000 RSI: ffffffff8132f254 RDI: 0000000000000007
RBP: ffff88809119fd28 R08: ffff888095aec580 R09: 0000000000000001
R10: ffffed1015d06bdf R11: ffff8880ae835efb R12: ffff8880aa587600
R13: ffff888095aecc68 R14: ffff888095aecd08 R15: ffff8880a8970908
FS:  0000000000ad5940(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000080 CR3: 0000000084bfc000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400