================================================================== BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:71 [inline] BUG: KASAN: use-after-free in atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline] BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:147 [inline] BUG: KASAN: use-after-free in skb_unref include/linux/skbuff.h:1131 [inline] BUG: KASAN: use-after-free in consume_skb+0x3c/0x250 net/core/skbuff.c:926 Read of size 4 at addr ffff88810f2f886c by task syz.2.1267/4793 CPU: 1 PID: 4793 Comm: syz.2.1267 Not tainted 5.15.167-syzkaller-00270-gef332e923197 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x151/0x1c0 lib/dump_stack.c:106 print_address_description+0x87/0x3b0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:427 [inline] kasan_report+0x179/0x1c0 mm/kasan/report.c:444 kasan_check_range+0x293/0x2a0 mm/kasan/generic.c:189 __kasan_check_read+0x11/0x20 mm/kasan/shadow.c:31 instrument_atomic_read include/linux/instrumented.h:71 [inline] atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline] refcount_read include/linux/refcount.h:147 [inline] skb_unref include/linux/skbuff.h:1131 [inline] consume_skb+0x3c/0x250 net/core/skbuff.c:926 __sk_msg_free+0x2dd/0x370 net/core/skmsg.c:205 sk_msg_free net/core/skmsg.c:218 [inline] __sk_psock_purge_ingress_msg net/core/skmsg.c:769 [inline] __sk_psock_zap_ingress net/core/skmsg.c:787 [inline] sk_psock_stop+0x44c/0x4d0 net/core/skmsg.c:805 sk_psock_drop+0x219/0x310 net/core/skmsg.c:844 sk_psock_put include/linux/skmsg.h:458 [inline] sock_map_unref+0x48f/0x4d0 net/core/sock_map.c:183 __sock_map_delete net/core/sock_map.c:425 [inline] sock_map_delete_from_link net/core/sock_map.c:438 [inline] sock_map_unlink net/core/sock_map.c:1497 [inline] sock_map_remove_links+0x41c/0x650 net/core/sock_map.c:1512 sock_map_close+0x114/0x530 net/core/sock_map.c:1549 unix_release+0x82/0xc0 net/unix/af_unix.c:936 __sock_release net/socket.c:649 [inline] sock_close+0xdf/0x270 net/socket.c:1336 __fput+0x228/0x8c0 fs/file_table.c:280 ____fput+0x15/0x20 fs/file_table.c:308 task_work_run+0x129/0x190 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0xc4/0xe0 kernel/entry/common.c:181 exit_to_user_mode_prepare+0x5a/0xa0 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x26/0x160 kernel/entry/common.c:307 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f404eaa8719 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:00007ffe433eb268 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 000000000002a45d RCX: 00007f404eaa8719 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007f404ec61a80 R08: 0000000000000001 R09: 00007ffe433eb55f R10: 00007f404e92a000 R11: 0000000000000246 R12: 000000000002a50c R13: 00007ffe433eb370 R14: 0000000000000032 R15: ffffffffffffffff Allocated by task 4794: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:433 [inline] __kasan_slab_alloc+0xb1/0xe0 mm/kasan/common.c:466 kasan_slab_alloc include/linux/kasan.h:217 [inline] slab_post_alloc_hook+0x53/0x2c0 mm/slab.h:550 slab_alloc_node mm/slub.c:3240 [inline] slab_alloc mm/slub.c:3248 [inline] kmem_cache_alloc+0xf5/0x200 mm/slub.c:3253 skb_clone+0x1d1/0x360 net/core/skbuff.c:1547 sk_psock_verdict_recv+0x53/0x840 net/core/skmsg.c:1183 unix_read_sock+0x132/0x370 net/unix/af_unix.c:2428 sk_psock_verdict_data_ready+0x147/0x1a0 net/core/skmsg.c:1226 unix_dgram_sendmsg+0x15fa/0x2090 net/unix/af_unix.c:1942 sock_sendmsg_nosec net/socket.c:704 [inline] __sock_sendmsg net/socket.c:716 [inline] ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2431 ___sys_sendmsg+0x252/0x2e0 net/socket.c:2485 __sys_sendmsg net/socket.c:2514 [inline] __do_sys_sendmsg net/socket.c:2523 [inline] __se_sys_sendmsg+0x19a/0x260 net/socket.c:2521 __x64_sys_sendmsg+0x7b/0x90 net/socket.c:2521 x64_sys_call+0x16a/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 Freed by task 3980: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:45 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370 ____kasan_slab_free+0x126/0x160 mm/kasan/common.c:365 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:373 kasan_slab_free include/linux/kasan.h:193 [inline] slab_free_hook mm/slub.c:1723 [inline] slab_free_freelist_hook+0xbd/0x190 mm/slub.c:1749 slab_free mm/slub.c:3519 [inline] kmem_cache_free+0x116/0x2e0 mm/slub.c:3535 kfree_skbmem+0x104/0x170 __kfree_skb net/core/skbuff.c:758 [inline] kfree_skb_reason net/core/skbuff.c:778 [inline] kfree_skb+0xc2/0x360 net/core/skbuff.c:792 sock_drop include/linux/skmsg.h:312 [inline] sk_psock_backlog+0xc21/0xd90 net/core/skmsg.c:682 process_one_work+0x6bb/0xc10 kernel/workqueue.c:2325 worker_thread+0xad5/0x12a0 kernel/workqueue.c:2472 kthread+0x421/0x510 kernel/kthread.c:337 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 The buggy address belongs to the object at ffff88810f2f8780 which belongs to the cache skbuff_head_cache of size 248 The buggy address is located 236 bytes inside of 248-byte region [ffff88810f2f8780, ffff88810f2f8878) The buggy address belongs to the page: page:ffffea00043cbe00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10f2f8 flags: 0x4000000000000200(slab|zone=1) raw: 4000000000000200 dead000000000100 dead000000000122 ffff8881081b3e00 raw: 0000000000000000 00000000000c000c 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 102, ts 4409073178, free_ts 4409024159 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x1a3/0x1b0 mm/page_alloc.c:2605 prep_new_page+0x1b/0x110 mm/page_alloc.c:2611 get_page_from_freelist+0x3550/0x35d0 mm/page_alloc.c:4485 __alloc_pages+0x27e/0x8f0 mm/page_alloc.c:5779 allocate_slab mm/slub.c:1932 [inline] new_slab+0x9a/0x4e0 mm/slub.c:1995 ___slab_alloc+0x39e/0x830 mm/slub.c:3028 __slab_alloc+0x4a/0x90 mm/slub.c:3115 slab_alloc_node mm/slub.c:3206 [inline] slab_alloc mm/slub.c:3248 [inline] kmem_cache_alloc+0x134/0x200 mm/slub.c:3253 kmem_cache_alloc_node include/linux/slab.h:474 [inline] __alloc_skb+0xbe/0x550 net/core/skbuff.c:416 alloc_skb include/linux/skbuff.h:1183 [inline] alloc_uevent_skb+0x80/0x230 lib/kobject_uevent.c:290 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline] kobject_uevent_net_broadcast+0x311/0x590 lib/kobject_uevent.c:409 kobject_uevent_env+0x525/0x700 lib/kobject_uevent.c:608 kobject_synth_uevent+0x4eb/0xae0 lib/kobject_uevent.c:208 store_uevent+0x16/0x30 kernel/module.c:1172 module_attr_store+0x5c/0x80 kernel/params.c:919 sysfs_kf_write+0x123/0x140 fs/sysfs/file.c:139 page last free stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] free_pages_prepare mm/page_alloc.c:1472 [inline] free_pcp_prepare mm/page_alloc.c:1544 [inline] free_unref_page_prepare+0x7c8/0x7d0 mm/page_alloc.c:3534 free_unref_page+0xe8/0x750 mm/page_alloc.c:3616 free_the_page mm/page_alloc.c:805 [inline] __free_pages+0x61/0xf0 mm/page_alloc.c:5855 free_pages+0x7c/0x90 mm/page_alloc.c:5866 selinux_genfs_get_sid+0x24d/0x2a0 security/selinux/hooks.c:1375 inode_doinit_with_dentry+0x8d2/0x1070 security/selinux/hooks.c:1570 selinux_d_instantiate+0x27/0x40 security/selinux/hooks.c:6489 security_d_instantiate+0x9f/0x100 security/security.c:2074 d_splice_alias+0x6d/0x390 fs/dcache.c:3071 kernfs_iop_lookup+0x29e/0x2f0 fs/kernfs/dir.c:1175 lookup_open fs/namei.c:3440 [inline] open_last_lookups fs/namei.c:3532 [inline] path_openat+0x1194/0x2f40 fs/namei.c:3739 do_filp_open+0x21c/0x460 fs/namei.c:3769 do_sys_openat2+0x13f/0x820 fs/open.c:1234 do_sys_open fs/open.c:1250 [inline] __do_sys_openat fs/open.c:1266 [inline] __se_sys_openat fs/open.c:1261 [inline] __x64_sys_openat+0x243/0x290 fs/open.c:1261 x64_sys_call+0x6bf/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:258 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80 Memory state around the buggy address: ffff88810f2f8700: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc ffff88810f2f8780: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88810f2f8800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc ^ ffff88810f2f8880: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ffff88810f2f8900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== ================================================================== BUG: KASAN: double-free or invalid-free in slab_free mm/slub.c:3519 [inline] BUG: KASAN: double-free or invalid-free in kmem_cache_free+0x116/0x2e0 mm/slub.c:3535 CPU: 1 PID: 4793 Comm: syz.2.1267 Tainted: G B 5.15.167-syzkaller-00270-gef332e923197 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x151/0x1c0 lib/dump_stack.c:106 print_address_description+0x87/0x3b0 mm/kasan/report.c:248 kasan_report_invalid_free+0x6b/0xa0 mm/kasan/report.c:370 ____kasan_slab_free+0x13e/0x160 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:373 kasan_slab_free include/linux/kasan.h:193 [inline] slab_free_hook mm/slub.c:1723 [inline] slab_free_freelist_hook+0xbd/0x190 mm/slub.c:1749 slab_free mm/slub.c:3519 [inline] kmem_cache_free+0x116/0x2e0 mm/slub.c:3535 kfree_skbmem+0x104/0x170 __kfree_skb net/core/skbuff.c:758 [inline] consume_skb+0xb4/0x250 net/core/skbuff.c:930 __sk_msg_free+0x2dd/0x370 net/core/skmsg.c:205 sk_msg_free net/core/skmsg.c:218 [inline] __sk_psock_purge_ingress_msg net/core/skmsg.c:769 [inline] __sk_psock_zap_ingress net/core/skmsg.c:787 [inline] sk_psock_stop+0x44c/0x4d0 net/core/skmsg.c:805 sk_psock_drop+0x219/0x310 net/core/skmsg.c:844 sk_psock_put include/linux/skmsg.h:458 [inline] sock_map_unref+0x48f/0x4d0 net/core/sock_map.c:183 __sock_map_delete net/core/sock_map.c:425 [inline] sock_map_delete_from_link net/core/sock_map.c:438 [inline] sock_map_unlink net/core/sock_map.c:1497 [inline] sock_map_remove_links+0x41c/0x650 net/core/sock_map.c:1512 sock_map_close+0x114/0x530 net/core/sock_map.c:1549 unix_release+0x82/0xc0 net/unix/af_unix.c:936 __sock_release net/socket.c:649 [inline] sock_close+0xdf/0x270 net/socket.c:1336 __fput+0x228/0x8c0 fs/file_table.c:280 ____fput+0x15/0x20 fs/file_table.c:308 task_work_run+0x129/0x190 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0xc4/0xe0 kernel/entry/common.c:181 exit_to_user_mode_prepare+0x5a/0xa0 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x26/0x160 kernel/entry/common.c:307 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f404eaa8719 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:00007ffe433eb268 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 000000000002a45d RCX: 00007f404eaa8719 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007f404ec61a80 R08: 0000000000000001 R09: 00007ffe433eb55f R10: 00007f404e92a000 R11: 0000000000000246 R12: 000000000002a50c R13: 00007ffe433eb370 R14: 0000000000000032 R15: ffffffffffffffff Allocated by task 4794: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:433 [inline] __kasan_slab_alloc+0xb1/0xe0 mm/kasan/common.c:466 kasan_slab_alloc include/linux/kasan.h:217 [inline] slab_post_alloc_hook+0x53/0x2c0 mm/slab.h:550 slab_alloc_node mm/slub.c:3240 [inline] slab_alloc mm/slub.c:3248 [inline] kmem_cache_alloc+0xf5/0x200 mm/slub.c:3253 skb_clone+0x1d1/0x360 net/core/skbuff.c:1547 sk_psock_verdict_recv+0x53/0x840 net/core/skmsg.c:1183 unix_read_sock+0x132/0x370 net/unix/af_unix.c:2428 sk_psock_verdict_data_ready+0x147/0x1a0 net/core/skmsg.c:1226 unix_dgram_sendmsg+0x15fa/0x2090 net/unix/af_unix.c:1942 sock_sendmsg_nosec net/socket.c:704 [inline] __sock_sendmsg net/socket.c:716 [inline] ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2431 ___sys_sendmsg+0x252/0x2e0 net/socket.c:2485 __sys_sendmsg net/socket.c:2514 [inline] __do_sys_sendmsg net/socket.c:2523 [inline] __se_sys_sendmsg+0x19a/0x260 net/socket.c:2521 __x64_sys_sendmsg+0x7b/0x90 net/socket.c:2521 x64_sys_call+0x16a/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 Freed by task 3980: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:45 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370 ____kasan_slab_free+0x126/0x160 mm/kasan/common.c:365 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:373 kasan_slab_free include/linux/kasan.h:193 [inline] slab_free_hook mm/slub.c:1723 [inline] slab_free_freelist_hook+0xbd/0x190 mm/slub.c:1749 slab_free mm/slub.c:3519 [inline] kmem_cache_free+0x116/0x2e0 mm/slub.c:3535 kfree_skbmem+0x104/0x170 __kfree_skb net/core/skbuff.c:758 [inline] kfree_skb_reason net/core/skbuff.c:778 [inline] kfree_skb+0xc2/0x360 net/core/skbuff.c:792 sock_drop include/linux/skmsg.h:312 [inline] sk_psock_backlog+0xc21/0xd90 net/core/skmsg.c:682 process_one_work+0x6bb/0xc10 kernel/workqueue.c:2325 worker_thread+0xad5/0x12a0 kernel/workqueue.c:2472 kthread+0x421/0x510 kernel/kthread.c:337 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 The buggy address belongs to the object at ffff88810f2f8780 which belongs to the cache skbuff_head_cache of size 248 The buggy address is located 0 bytes inside of 248-byte region [ffff88810f2f8780, ffff88810f2f8878) The buggy address belongs to the page: page:ffffea00043cbe00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10f2f8 flags: 0x4000000000000200(slab|zone=1) raw: 4000000000000200 dead000000000100 dead000000000122 ffff8881081b3e00 raw: 0000000000000000 00000000000c000c 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 102, ts 4409073178, free_ts 4409024159 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x1a3/0x1b0 mm/page_alloc.c:2605 prep_new_page+0x1b/0x110 mm/page_alloc.c:2611 get_page_from_freelist+0x3550/0x35d0 mm/page_alloc.c:4485 __alloc_pages+0x27e/0x8f0 mm/page_alloc.c:5779 allocate_slab mm/slub.c:1932 [inline] new_slab+0x9a/0x4e0 mm/slub.c:1995 ___slab_alloc+0x39e/0x830 mm/slub.c:3028 __slab_alloc+0x4a/0x90 mm/slub.c:3115 slab_alloc_node mm/slub.c:3206 [inline] slab_alloc mm/slub.c:3248 [inline] kmem_cache_alloc+0x134/0x200 mm/slub.c:3253 kmem_cache_alloc_node include/linux/slab.h:474 [inline] __alloc_skb+0xbe/0x550 net/core/skbuff.c:416 alloc_skb include/linux/skbuff.h:1183 [inline] alloc_uevent_skb+0x80/0x230 lib/kobject_uevent.c:290 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline] kobject_uevent_net_broadcast+0x311/0x590 lib/kobject_uevent.c:409 kobject_uevent_env+0x525/0x700 lib/kobject_uevent.c:608 kobject_synth_uevent+0x4eb/0xae0 lib/kobject_uevent.c:208 store_uevent+0x16/0x30 kernel/module.c:1172 module_attr_store+0x5c/0x80 kernel/params.c:919 sysfs_kf_write+0x123/0x140 fs/sysfs/file.c:139 page last free stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] free_pages_prepare mm/page_alloc.c:1472 [inline] free_pcp_prepare mm/page_alloc.c:1544 [inline] free_unref_page_prepare+0x7c8/0x7d0 mm/page_alloc.c:3534 free_unref_page+0xe8/0x750 mm/page_alloc.c:3616 free_the_page mm/page_alloc.c:805 [inline] __free_pages+0x61/0xf0 mm/page_alloc.c:5855 free_pages+0x7c/0x90 mm/page_alloc.c:5866 selinux_genfs_get_sid+0x24d/0x2a0 security/selinux/hooks.c:1375 inode_doinit_with_dentry+0x8d2/0x1070 security/selinux/hooks.c:1570 selinux_d_instantiate+0x27/0x40 security/selinux/hooks.c:6489 security_d_instantiate+0x9f/0x100 security/security.c:2074 d_splice_alias+0x6d/0x390 fs/dcache.c:3071 kernfs_iop_lookup+0x29e/0x2f0 fs/kernfs/dir.c:1175 lookup_open fs/namei.c:3440 [inline] open_last_lookups fs/namei.c:3532 [inline] path_openat+0x1194/0x2f40 fs/namei.c:3739 do_filp_open+0x21c/0x460 fs/namei.c:3769 do_sys_openat2+0x13f/0x820 fs/open.c:1234 do_sys_open fs/open.c:1250 [inline] __do_sys_openat fs/open.c:1266 [inline] __se_sys_openat fs/open.c:1261 [inline] __x64_sys_openat+0x243/0x290 fs/open.c:1261 x64_sys_call+0x6bf/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:258 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80 Memory state around the buggy address: ffff88810f2f8680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88810f2f8700: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc >ffff88810f2f8780: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88810f2f8800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc ffff88810f2f8880: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ==================================================================