Kernel bug: KASAN: slab-use-after-free Read in lane_ioctl
Subsystem: net
Status: fixed

Crash report:
==================================================================
BUG: KASAN: slab-use-after-free in lecd_attach net/atm/lec.c:751 [inline]
BUG: KASAN: slab-use-after-free in lane_ioctl+0x2224/0x23e0 net/atm/lec.c:1008
Read of size 8 at addr ffff88807c7b8e68 by task syz.1.17/6142

CPU: 1 UID: 0 PID: 6142 Comm: syz.1.17 Not tainted 6.16.0-rc1-syzkaller-00239-g08215f5486ec #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xcd/0x680 mm/kasan/report.c:521
 kasan_report+0xe0/0x110 mm/kasan/report.c:634
 lecd_attach net/atm/lec.c:751 [inline]
 lane_ioctl+0x2224/0x23e0 net/atm/lec.c:1008
 do_vcc_ioctl+0x12c/0x930 net/atm/ioctl.c:159
 sock_do_ioctl+0x118/0x280 net/socket.c:1190
 sock_ioctl+0x227/0x6b0 net/socket.c:1311
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl fs/ioctl.c:893 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc55f38e929
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc56028f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc55f5b5fa0 RCX: 00007fc55f38e929
RDX: 0000000000000000 RSI: 00000000000061d0 RDI: 0000000000000005
RBP: 00007fc55f410b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fc55f5b5fa0 R15: 00007fff0ede2e48
 </TASK>

Allocated by task 6132:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4328 [inline]
 __kvmalloc_node_noprof+0x27b/0x620 mm/slub.c:5015
 alloc_netdev_mqs+0xd2/0x1570 net/core/dev.c:11711
 lecd_attach net/atm/lec.c:737 [inline]
 lane_ioctl+0x17db/0x23e0 net/atm/lec.c:1008
 do_vcc_ioctl+0x12c/0x930 net/atm/ioctl.c:159
 sock_do_ioctl+0x118/0x280 net/socket.c:1190
 sock_ioctl+0x227/0x6b0 net/socket.c:1311
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl fs/ioctl.c:893 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 6132:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x51/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2381 [inline]
 slab_free mm/slub.c:4643 [inline]
 kfree+0x2b4/0x4d0 mm/slub.c:4842
 free_netdev+0x6c5/0x910 net/core/dev.c:11892
 lecd_attach net/atm/lec.c:744 [inline]
 lane_ioctl+0x1ce8/0x23e0 net/atm/lec.c:1008
 do_vcc_ioctl+0x12c/0x930 net/atm/ioctl.c:159
 sock_do_ioctl+0x118/0x280 net/socket.c:1190
 sock_ioctl+0x227/0x6b0 net/socket.c:1311
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl fs/ioctl.c:893 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88807c7b8000
 which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 3688 bytes inside of
 freed 4096-byte region [ffff88807c7b8000, ffff88807c7b9000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88807c7be000 pfn:0x7c7b8
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888077790a81
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff88801b84b500 ffffea00016b0210 ffffea0000a38c10
raw: ffff88807c7be000 0000000000040001 00000000f5000000 ffff888077790a81
head: 00fff00000000240 ffff88801b84b500 ffffea00016b0210 ffffea0000a38c10
head: ffff88807c7be000 0000000000040001 00000000f5000000 ffff888077790a81
head: 00fff00000000003 ffffea0001f1ee01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5876, tgid 5876 (syz-executor), ts 115146069114, free_ts 115116949410
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419
 alloc_slab_page mm/slub.c:2451 [inline]
 allocate_slab mm/slub.c:2619 [inline]
 new_slab+0x23b/0x330 mm/slub.c:2673
 ___slab_alloc+0xd9c/0x1940 mm/slub.c:3859
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3949
 __slab_alloc_node mm/slub.c:4024 [inline]
 slab_alloc_node mm/slub.c:4185 [inline]
 __do_kmalloc_node mm/slub.c:4327 [inline]
 __kmalloc_noprof+0x2f2/0x510 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 __register_sysctl_table+0xb3/0x1900 fs/proc/proc_sysctl.c:1376
 __addrconf_sysctl_register+0x1a2/0x360 net/ipv6/addrconf.c:7248
 addrconf_sysctl_register net/ipv6/addrconf.c:7296 [inline]
 addrconf_sysctl_register+0x15f/0x1f0 net/ipv6/addrconf.c:7285
 ipv6_add_dev+0xb39/0x15f0 net/ipv6/addrconf.c:458
 addrconf_notify+0x53e/0x19e0 net/ipv6/addrconf.c:3654
 notifier_call_chain+0xbc/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2230
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 register_netdevice+0x182e/0x2270 net/core/dev.c:11143
page last free pid 5880 tgid 5880 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_frozen_pages+0x7fe/0x1180 mm/page_alloc.c:2706
 discard_slab mm/slub.c:2717 [inline]
 __put_partials+0x16d/0x1c0 mm/slub.c:3186
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x4d/0x120 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4148 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 __do_kmalloc_node mm/slub.c:4327 [inline]
 __kmalloc_noprof+0x1d4/0x510 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 tomoyo_realpath_from_path+0xc2/0x6e0 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x274/0x460 security/tomoyo/file.c:822
 security_inode_getattr+0x116/0x290 security/security.c:2377
 vfs_getattr fs/stat.c:259 [inline]
 vfs_fstat+0x4b/0xe0 fs/stat.c:281
 __do_sys_newfstat+0x87/0x100 fs/stat.c:555
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88807c7b8d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807c7b8d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807c7b8e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                          ^
 ffff88807c7b8e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807c7b8f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
==================================================================
BUG: KASAN: slab-use-after-free in lec_arp_init net/atm/lec.c:1239 [inline]
BUG: KASAN: slab-use-after-free in lecd_attach net/atm/lec.c:754 [inline]
BUG: KASAN: slab-use-after-free in lane_ioctl+0x1d43/0x23e0 net/atm/lec.c:1008
Write of size 8 at addr ffff88807c7b8d90 by task syz.1.17/6142

CPU: 0 UID: 0 PID: 6142 Comm: syz.1.17 Tainted: G    B               6.16.0-rc1-syzkaller-00239-g08215f5486ec #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xcd/0x680 mm/kasan/report.c:521
 kasan_report+0xe0/0x110 mm/kasan/report.c:634
 lec_arp_init net/atm/lec.c:1239 [inline]
 lecd_attach net/atm/lec.c:754 [inline]
 lane_ioctl+0x1d43/0x23e0 net/atm/lec.c:1008
 do_vcc_ioctl+0x12c/0x930 net/atm/ioctl.c:159
 sock_do_ioctl+0x118/0x280 net/socket.c:1190
 sock_ioctl+0x227/0x6b0 net/socket.c:1311
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl fs/ioctl.c:893 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc55f38e929
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc56028f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc55f5b5fa0 RCX: 00007fc55f38e929
RDX: 0000000000000000 RSI: 00000000000061d0 RDI: 0000000000000005
RBP: 00007fc55f410b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fc55f5b5fa0 R15: 00007fff0ede2e48
 </TASK>

Allocated by task 6132:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4328 [inline]
 __kvmalloc_node_noprof+0x27b/0x620 mm/slub.c:5015
 alloc_netdev_mqs+0xd2/0x1570 net/core/dev.c:11711
 lecd_attach net/atm/lec.c:737 [inline]
 lane_ioctl+0x17db/0x23e0 net/atm/lec.c:1008
 do_vcc_ioctl+0x12c/0x930 net/atm/ioctl.c:159
 sock_do_ioctl+0x118/0x280 net/socket.c:1190
 sock_ioctl+0x227/0x6b0 net/socket.c:1311
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl fs/ioctl.c:893 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 6132:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x51/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2381 [inline]
 slab_free mm/slub.c:4643 [inline]
 kfree+0x2b4/0x4d0 mm/slub.c:4842
 free_netdev+0x6c5/0x910 net/core/dev.c:11892
 lecd_attach net/atm/lec.c:744 [inline]
 lane_ioctl+0x1ce8/0x23e0 net/atm/lec.c:1008
 do_vcc_ioctl+0x12c/0x930 net/atm/ioctl.c:159
 sock_do_ioctl+0x118/0x280 net/socket.c:1190
 sock_ioctl+0x227/0x6b0 net/socket.c:1311
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl fs/ioctl.c:893 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88807c7b8000
 which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 3472 bytes inside of
 freed 4096-byte region [ffff88807c7b8000, ffff88807c7b9000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7c7b8
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888077790a81
anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b84b500 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000040004 00000000f5000000 ffff888077790a81
head: 00fff00000000040 ffff88801b84b500 0000000000000000 dead000000000001
head: 0000000000000000 0000000000040004 00000000f5000000 ffff888077790a81
head: 00fff00000000003 ffffea0001f1ee01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5876, tgid 5876 (syz-executor), ts 115146069114, free_ts 115116949410
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419
 alloc_slab_page mm/slub.c:2451 [inline]
 allocate_slab mm/slub.c:2619 [inline]
 new_slab+0x23b/0x330 mm/slub.c:2673
 ___slab_alloc+0xd9c/0x1940 mm/slub.c:3859
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3949
 __slab_alloc_node mm/slub.c:4024 [inline]
 slab_alloc_node mm/slub.c:4185 [inline]
 __do_kmalloc_node mm/slub.c:4327 [inline]
 __kmalloc_noprof+0x2f2/0x510 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 __register_sysctl_table+0xb3/0x1900 fs/proc/proc_sysctl.c:1376
 __addrconf_sysctl_register+0x1a2/0x360 net/ipv6/addrconf.c:7248
 addrconf_sysctl_register net/ipv6/addrconf.c:7296 [inline]
 addrconf_sysctl_register+0x15f/0x1f0 net/ipv6/addrconf.c:7285
 ipv6_add_dev+0xb39/0x15f0 net/ipv6/addrconf.c:458
 addrconf_notify+0x53e/0x19e0 net/ipv6/addrconf.c:3654
 notifier_call_chain+0xbc/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2230
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 register_netdevice+0x182e/0x2270 net/core/dev.c:11143
page last free pid 5880 tgid 5880 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_frozen_pages+0x7fe/0x1180 mm/page_alloc.c:2706
 discard_slab mm/slub.c:2717 [inline]
 __put_partials+0x16d/0x1c0 mm/slub.c:3186
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x4d/0x120 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4148 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 __do_kmalloc_node mm/slub.c:4327 [inline]
 __kmalloc_noprof+0x1d4/0x510 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 tomoyo_realpath_from_path+0xc2/0x6e0 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x274/0x460 security/tomoyo/file.c:822
 security_inode_getattr+0x116/0x290 security/security.c:2377
 vfs_getattr fs/stat.c:259 [inline]
 vfs_fstat+0x4b/0xe0 fs/stat.c:281
 __do_sys_newfstat+0x87/0x100 fs/stat.c:555
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88807c7b8c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807c7b8d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807c7b8d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff88807c7b8e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807c7b8e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================