syzbot

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BUG: KASAN: unknown-crash in futex_wake+0x382/0x580 kernel/futex/waitwake.c:191
Read of size 8 at addr ffffc900039dfad8 by task syz.1.9500/26050

CPU: 1 UID: 0 PID: 26050 Comm: syz.1.9500 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 futex_wake+0x382/0x580 kernel/futex/waitwake.c:191
 do_futex+0x395/0x420 kernel/futex/syscalls.c:135
 __do_sys_futex kernel/futex/syscalls.c:207 [inline]
 __se_sys_futex+0x3a8/0x450 kernel/futex/syscalls.c:188
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3eb3b9ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3eb3f3fba8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00000000000002d0 RCX: 00007f3eb3b9ce59
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f3eb3e16278
RBP: 00000000000010e9 R08: 0000000000000000 R09: 0000000000000000
R10: 00007f3eb3e15fa0 R11: 0000000000000246 R12: 0000000000000003
R13: 00007f3eb3e1627c R14: 00007f3eb3e16278 R15: 00007f3eb3e16270
 </TASK>

The buggy address belongs to a vmalloc virtual mapping
The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xa29e7
memcg:ffff888030daa402
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff ffff888030daa402
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x1029c2(GFP_NOWAIT|__GFP_HIGHMEM|__GFP_IO|__GFP_FS|__GFP_ZERO|__GFP_HARDWALL), pid 26050, tgid 26050 (syz.1.9500), ts 2021430196564, free_ts 2021372410361
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1858
 prep_new_page mm/page_alloc.c:1866 [inline]
 get_page_from_freelist+0x24ba/0x2540 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226
 alloc_pages_mpol+0x235/0x490 mm/mempolicy.c:2490
 alloc_frozen_pages_noprof mm/mempolicy.c:2561 [inline]
 alloc_pages_noprof+0xac/0x2a0 mm/mempolicy.c:2581
 vm_area_alloc_pages mm/vmalloc.c:3653 [inline]
 __vmalloc_area_node mm/vmalloc.c:3878 [inline]
 __vmalloc_node_range_noprof+0x7a7/0x1750 mm/vmalloc.c:4064
 __vmalloc_node_noprof+0xc2/0x100 mm/vmalloc.c:4124
 alloc_thread_stack_node kernel/fork.c:357 [inline]
 dup_task_struct+0x298/0x840 kernel/fork.c:926
 copy_process+0x89b/0x4440 kernel/fork.c:2090
 kernel_clone+0x284/0x8f0 kernel/fork.c:2721
 __do_sys_clone3 kernel/fork.c:3025 [inline]
 __se_sys_clone3+0x33c/0x360 kernel/fork.c:3004
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 26050 tgid 26050 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1402 [inline]
 __free_frozen_pages+0xbc7/0xd30 mm/page_alloc.c:2943
 __slab_free+0x274/0x2c0 mm/slub.c:5613
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4570 [inline]
 slab_alloc_node mm/slub.c:4899 [inline]
 kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4906
 vm_area_dup+0x2b/0x680 mm/vma_init.c:123
 __split_vma+0x1dc/0xa40 mm/vma.c:516
 split_vma mm/vma.c:599 [inline]
 vma_modify+0x88a/0x1e10 mm/vma.c:1691
 vma_modify_flags+0x24b/0x330 mm/vma.c:1719
 mprotect_fixup+0x62a/0xb60 mm/mprotect.c:789
 do_mprotect_pkey+0x8d5/0xd20 mm/mprotect.c:967
 __do_sys_mprotect mm/mprotect.c:988 [inline]
 __se_sys_mprotect mm/mprotect.c:985 [inline]
 __x64_sys_mprotect+0x80/0x90 mm/mprotect.c:985
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffffc900039df980: 67 c8 a7 42 00 00 00 00 67 d8 a7 42 00 00 00 00
 ffffc900039dfa00: 67 e8 a7 42 00 00 00 00 67 f8 a7 42 00 00 00 00
>ffffc900039dfa80: f1 f1 f1 f1 00 00 00 00 67 18 a8 42 00 00 00 00
                                                    ^
 ffffc900039dfb00: 00 00 00 00 00 f3 f3 f3 f3 f3 f3 f3 f3 f3 f3 f3
 ffffc900039dfb80: 67 48 a8 42 00 00 00 00 67 58 a8 42 00 00 00 00
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