syzbot

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BUG: KASAN: slab-use-after-free in __task_pid_nr_ns+0x1da/0x470 kernel/pid.c:517
Read of size 8 at addr ffff88802dc1d2a8 by task syz.4.167/6558

CPU: 1 UID: 0 PID: 6558 Comm: syz.4.167 Not tainted 6.17.0-rc1-syzkaller-g9e293d47bfb9 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 __task_pid_nr_ns+0x1da/0x470 kernel/pid.c:517
 perf_event_pid_type kernel/events/core.c:1431 [inline]
 perf_event_pid kernel/events/core.c:1440 [inline]
 perf_event_read_event kernel/events/core.c:8539 [inline]
 sync_child_event kernel/events/core.c:13982 [inline]
 perf_child_detach kernel/events/core.c:2339 [inline]
 __perf_remove_from_context+0x22e5/0x2a80 kernel/events/core.c:2510
 perf_remove_from_context+0x152/0x1d0 kernel/events/core.c:2559
 perf_event_release_kernel+0x2dd/0x510 kernel/events/core.c:5837
 perf_release+0x38/0x50 kernel/events/core.c:5870
 __fput+0x44c/0xa70 fs/file_table.c:468
 task_work_run+0x1d4/0x260 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f110358ebe9
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:00007ffdef5f4e18 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f11037b7da0 RCX: 00007f110358ebe9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f11037b7da0 R08: 000000000000251c R09: 0000001def5f510f
R10: 00007f11037b7cb0 R11: 0000000000000246 R12: 00000000000209f4
R13: 00007ffdef5f4f10 R14: ffffffffffffffff R15: 00007ffdef5f4f30
 </TASK>

Allocated by task 6560:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:330 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:356
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4180 [inline]
 slab_alloc_node mm/slub.c:4229 [inline]
 kmem_cache_alloc_noprof+0x1c1/0x3c0 mm/slub.c:4236
 copy_signal+0x50/0x630 kernel/fork.c:1655
 copy_process+0x16a6/0x3c00 kernel/fork.c:2172
 kernel_clone+0x21e/0x840 kernel/fork.c:2605
 __do_sys_clone kernel/fork.c:2748 [inline]
 __se_sys_clone kernel/fork.c:2732 [inline]
 __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2732
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88802dc1d100
 which belongs to the cache signal_cache of size 1544
The buggy address is located 424 bytes inside of
 freed 1544-byte region [ffff88802dc1d100, ffff88802dc1d708)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2dc18
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888077f3f501
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801bad5780 dead000000000100 dead000000000122
raw: 0000000000000000 0000000080120012 00000000f5000000 ffff888077f3f501
head: 00fff00000000040 ffff88801bad5780 dead000000000100 dead000000000122
head: 0000000000000000 0000000080120012 00000000f5000000 ffff888077f3f501
head: 00fff00000000003 ffffea0000b70601 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 198, tgid 198 (kworker/u8:5), ts 22619643804, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:2487 [inline]
 allocate_slab+0x8a/0x370 mm/slub.c:2655
 new_slab mm/slub.c:2709 [inline]
 ___slab_alloc+0xbeb/0x1410 mm/slub.c:3891
 __slab_alloc mm/slub.c:3981 [inline]
 __slab_alloc_node mm/slub.c:4056 [inline]
 slab_alloc_node mm/slub.c:4217 [inline]
 kmem_cache_alloc_noprof+0x283/0x3c0 mm/slub.c:4236
 copy_signal+0x50/0x630 kernel/fork.c:1655
 copy_process+0x16a6/0x3c00 kernel/fork.c:2172
 kernel_clone+0x21e/0x840 kernel/fork.c:2605
 user_mode_thread+0xdd/0x140 kernel/fork.c:2683
 call_usermodehelper_exec_work+0x5c/0x230 kernel/umh.c:171
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88802dc1d180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802dc1d200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802dc1d280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff88802dc1d300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802dc1d380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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