RDX: 0000000000000001 RSI: 00000000200063c0 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffd1b088cf7 R09: 00007f063926d335
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 00007f06392708c1
 </TASK>
==================================================================
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 ffff88811d2815ec by task syz-executor258/295

CPU: 0 PID: 295 Comm: syz-executor258 Not tainted 5.15.131-syzkaller-00653-gea586874d2f9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x151/0x1b7 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:768 [inline]
 __sk_psock_zap_ingress net/core/skmsg.c:786 [inline]
 sk_psock_stop+0x44c/0x4d0 net/core/skmsg.c:804
 sock_map_close+0x2b9/0x4c0 net/core/sock_map.c:1544
 unix_release+0x82/0xc0 net/unix/af_unix.c:949
 __sock_release net/socket.c:649 [inline]
 sock_close+0xdf/0x270 net/socket.c:1317
 __fput+0x3fe/0x910 fs/file_table.c:280
 ____fput+0x15/0x20 fs/file_table.c:308
 task_work_run+0x129/0x190 kernel/task_work.c:164
 ptrace_notify+0x29e/0x350 kernel/signal.c:2383
 ptrace_report_syscall include/linux/tracehook.h:66 [inline]
 tracehook_report_syscall_exit include/linux/tracehook.h:130 [inline]
 arch_syscall_exit_tracehook include/linux/entry-common.h:297 [inline]
 syscall_exit_work kernel/entry/common.c:256 [inline]
 syscall_exit_to_user_mode_prepare kernel/entry/common.c:283 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:288 [inline]
 syscall_exit_to_user_mode+0xac/0x160 kernel/entry/common.c:301
 do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f0639229d70
Code: 00 00 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d4 e8 40 2c 00 00 80 3d 11 33 07 00 00 74 17 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c
RSP: 002b:00007ffd1b088f58 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00007f0639229d70
RDX: 0000000000000001 RSI: 00000000200063c0 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffd1b088cf7 R09: 00007f063926d335
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 00007f06392708c1
 </TASK>

Allocated by task 295:
 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:1182
 unix_read_sock+0x132/0x370 net/unix/af_unix.c:2433
 sk_psock_verdict_data_ready+0x147/0x1a0 net/core/skmsg.c:1225
 unix_dgram_sendmsg+0x15fa/0x2090 net/unix/af_unix.c:1949
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg net/socket.c:724 [inline]
 ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2412
 ___sys_sendmsg+0x252/0x2e0 net/socket.c:2466
 __sys_sendmmsg+0x2bf/0x530 net/socket.c:2552
 __do_sys_sendmmsg net/socket.c:2581 [inline]
 __se_sys_sendmmsg net/socket.c:2578 [inline]
 __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2578
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 20:
 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:681
 process_one_work+0x6bb/0xc10 kernel/workqueue.c:2317
 worker_thread+0xad5/0x12a0 kernel/workqueue.c:2464
 kthread+0x421/0x510 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

The buggy address belongs to the object at ffff88811d281500
 which belongs to the cache skbuff_head_cache of size 248
The buggy address is located 236 bytes inside of
 248-byte region [ffff88811d281500, ffff88811d2815f8)
The buggy address belongs to the page:
page:ffffea000474a040 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11d281
flags: 0x4000000000000200(slab|zone=1)
raw: 4000000000000200 0000000000000000 dead000000000122 ffff888100351080
raw: 0000000000000000 00000000800c000c 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 0x12a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY), pid 295, ts 22768934490, free_ts 15532055566
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1a3/0x1b0 mm/page_alloc.c:2602
 prep_new_page+0x1b/0x110 mm/page_alloc.c:2608
 get_page_from_freelist+0x3550/0x35d0 mm/page_alloc.c:4482
 __alloc_pages+0x206/0x5e0 mm/page_alloc.c:5773
 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]
 nlmsg_new include/net/netlink.h:953 [inline]
 audit_buffer_alloc kernel/audit.c:1782 [inline]
 audit_log_start+0x456/0xa80 kernel/audit.c:1900
 common_lsm_audit+0xd8/0x18b0 security/lsm_audit.c:457
 slow_avc_audit+0x26c/0x3c0 security/selinux/avc.c:802
 avc_audit security/selinux/include/avc.h:135 [inline]
 cred_has_capability security/selinux/hooks.c:1677 [inline]
 selinux_capable+0x279/0x430 security/selinux/hooks.c:2193
 security_capable+0x77/0xb0 security/security.c:808
 ns_capable_common kernel/capability.c:375 [inline]
 ns_capable kernel/capability.c:396 [inline]
 capable+0x6d/0xe0 kernel/capability.c:449
 perfmon_capable include/linux/capability.h:259 [inline]
 bpf_allow_ptr_leaks include/linux/bpf.h:1495 [inline]
 bpf_check+0x1916/0x12bf0 kernel/bpf/verifier.c:13984
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1469 [inline]
 free_pcp_prepare mm/page_alloc.c:1541 [inline]
 free_unref_page_prepare+0x7c8/0x7d0 mm/page_alloc.c:3531
 free_unref_page+0xe6/0x730 mm/page_alloc.c:3613
 __put_single_page mm/swap.c:98 [inline]
 __put_page+0xb0/0xe0 mm/swap.c:129
 put_page include/linux/mm.h:1295 [inline]
 anon_pipe_buf_release+0x187/0x200 fs/pipe.c:137
 pipe_buf_release include/linux/pipe_fs_i.h:203 [inline]
 pipe_read+0x5a6/0x1040 fs/pipe.c:323
 call_read_iter include/linux/fs.h:2153 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0xa7e/0xd40 fs/read_write.c:485
 ksys_read+0x199/0x2c0 fs/read_write.c:623
 __do_sys_read fs/read_write.c:633 [inline]
 __se_sys_read fs/read_write.c:631 [inline]
 __x64_sys_read+0x7b/0x90 fs/read_write.c:631
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Memory state around the buggy address:
 ffff88811d281480: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc
 ffff88811d281500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88811d281580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc
                                                          ^
 ffff88811d281600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88811d281680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
==================================================================
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: 0 PID: 295 Comm: syz-executor258 Tainted: G    B             5.15.131-syzkaller-00653-gea586874d2f9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x151/0x1b7 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:768 [inline]
 __sk_psock_zap_ingress net/core/skmsg.c:786 [inline]
 sk_psock_stop+0x44c/0x4d0 net/core/skmsg.c:804
 sock_map_close+0x2b9/0x4c0 net/core/sock_map.c:1544
 unix_release+0x82/0xc0 net/unix/af_unix.c:949
 __sock_release net/socket.c:649 [inline]
 sock_close+0xdf/0x270 net/socket.c:1317
 __fput+0x3fe/0x910 fs/file_table.c:280
 ____fput+0x15/0x20 fs/file_table.c:308
 task_work_run+0x129/0x190 kernel/task_work.c:164
 ptrace_notify+0x29e/0x350 kernel/signal.c:2383
 ptrace_report_syscall include/linux/tracehook.h:66 [inline]
 tracehook_report_syscall_exit include/linux/tracehook.h:130 [inline]
 arch_syscall_exit_tracehook include/linux/entry-common.h:297 [inline]
 syscall_exit_work kernel/entry/common.c:256 [inline]
 syscall_exit_to_user_mode_prepare kernel/entry/common.c:283 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:288 [inline]
 syscall_exit_to_user_mode+0xac/0x160 kernel/entry/common.c:301
 do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f0639229d70
Code: 00 00 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d4 e8 40 2c 00 00 80 3d 11 33 07 00 00 74 17 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c
RSP: 002b:00007ffd1b088f58 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00007f0639229d70
RDX: 0000000000000001 RSI: 00000000200063c0 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffd1b088cf7 R09: 00007f063926d335
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 00007f06392708c1
 </TASK>

Allocated by task 295:
 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:1182
 unix_read_sock+0x132/0x370 net/unix/af_unix.c:2433
 sk_psock_verdict_data_ready+0x147/0x1a0 net/core/skmsg.c:1225
 unix_dgram_sendmsg+0x15fa/0x2090 net/unix/af_unix.c:1949
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg net/socket.c:724 [inline]
 ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2412
 ___sys_sendmsg+0x252/0x2e0 net/socket.c:2466
 __sys_sendmmsg+0x2bf/0x530 net/socket.c:2552
 __do_sys_sendmmsg net/socket.c:2581 [inline]
 __se_sys_sendmmsg net/socket.c:2578 [inline]
 __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2578
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 20:
 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:681
 process_one_work+0x6bb/0xc10 kernel/workqueue.c:2317
 worker_thread+0xad5/0x12a0 kernel/workqueue.c:2464
 kthread+0x421/0x510 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

The buggy address belongs to the object at ffff88811d281500
 which belongs to the cache skbuff_head_cache of size 248
The buggy address is located 0 bytes inside of
 248-byte region [ffff88811d281500, ffff88811d2815f8)
The buggy address belongs to the page:
page:ffffea000474a040 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11d281
flags: 0x4000000000000200(slab|zone=1)
raw: 4000000000000200 0000000000000000 dead000000000122 ffff888100351080
raw: 0000000000000000 00000000800c000c 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 0x12a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY), pid 295, ts 22768934490, free_ts 15532055566
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1a3/0x1b0 mm/page_alloc.c:2602
 prep_new_page+0x1b/0x110 mm/page_alloc.c:2608
 get_page_from_freelist+0x3550/0x35d0 mm/page_alloc.c:4482
 __alloc_pages+0x206/0x5e0 mm/page_alloc.c:5773
 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]
 nlmsg_new include/net/netlink.h:953 [inline]
 audit_buffer_alloc kernel/audit.c:1782 [inline]
 audit_log_start+0x456/0xa80 kernel/audit.c:1900
 common_lsm_audit+0xd8/0x18b0 security/lsm_audit.c:457
 slow_avc_audit+0x26c/0x3c0 security/selinux/avc.c:802
 avc_audit security/selinux/include/avc.h:135 [inline]
 cred_has_capability security/selinux/hooks.c:1677 [inline]
 selinux_capable+0x279/0x430 security/selinux/hooks.c:2193
 security_capable+0x77/0xb0 security/security.c:808
 ns_capable_common kernel/capability.c:375 [inline]
 ns_capable kernel/capability.c:396 [inline]
 capable+0x6d/0xe0 kernel/capability.c:449
 perfmon_capable include/linux/capability.h:259 [inline]
 bpf_allow_ptr_leaks include/linux/bpf.h:1495 [inline]
 bpf_check+0x1916/0x12bf0 kernel/bpf/verifier.c:13984
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1469 [inline]
 free_pcp_prepare mm/page_alloc.c:1541 [inline]
 free_unref_page_prepare+0x7c8/0x7d0 mm/page_alloc.c:3531
 free_unref_page+0xe6/0x730 mm/page_alloc.c:3613
 __put_single_page mm/swap.c:98 [inline]
 __put_page+0xb0/0xe0 mm/swap.c:129
 put_page include/linux/mm.h:1295 [inline]
 anon_pipe_buf_release+0x187/0x200 fs/pipe.c:137
 pipe_buf_release include/linux/pipe_fs_i.h:203 [inline]
 pipe_read+0x5a6/0x1040 fs/pipe.c:323
 call_read_iter include/linux/fs.h:2153 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0xa7e/0xd40 fs/read_write.c:485
 ksys_read+0x199/0x2c0 fs/read_write.c:623
 __do_sys_read fs/read_write.c:633 [inline]
 __se_sys_read fs/read_write.c:631 [inline]
 __x64_sys_read+0x7b/0x90 fs/read_write.c:631
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Memory state around the buggy address:
 ffff88811d281400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88811d281480: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc
>ffff88811d281500: