syzbot

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BUG: KASAN: stack-out-of-bounds in vhost_task_fn+0x31d/0x360 kernel/vhost_task.c:55
Read of size 8 at addr ffffc90012807e30 by task vhost-966/967

CPU: 0 PID: 967 Comm: vhost-966 Not tainted 6.4.0-syzkaller-11312-gb5641a5d8b8b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:364
 print_report mm/kasan/report.c:475 [inline]
 kasan_report+0x11d/0x130 mm/kasan/report.c:588
 vhost_task_fn+0x31d/0x360 kernel/vhost_task.c:55
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </TASK>

The buggy address belongs to the virtual mapping at
 [ffffc90012800000, ffffc90012809000) created by:
 kernel_clone+0xeb/0x890 kernel/fork.c:2911

The buggy address belongs to the physical page:
page:ffffea000206c640 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x81b19
memcg:ffff88806838d102
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff ffff88806838d102
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x102dc2(GFP_HIGHUSER|__GFP_NOWARN|__GFP_ZERO), pid 964, tgid 964 (syz-executor.1), ts 2689909716000, free_ts 2689429092823
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x2db/0x350 mm/page_alloc.c:1570
 prep_new_page mm/page_alloc.c:1577 [inline]
 get_page_from_freelist+0xfed/0x2d30 mm/page_alloc.c:3221
 __alloc_pages+0x1cb/0x4a0 mm/page_alloc.c:4477
 alloc_pages+0x1aa/0x270 mm/mempolicy.c:2279
 vm_area_alloc_pages mm/vmalloc.c:3059 [inline]
 __vmalloc_area_node mm/vmalloc.c:3135 [inline]
 __vmalloc_node_range+0xb1c/0x14c0 mm/vmalloc.c:3316
 alloc_thread_stack_node kernel/fork.c:309 [inline]
 dup_task_struct kernel/fork.c:1112 [inline]
 copy_process+0x13bb/0x75c0 kernel/fork.c:2329
 kernel_clone+0xeb/0x890 kernel/fork.c:2911
 __do_sys_clone+0xba/0x100 kernel/fork.c:3054
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1161 [inline]
 free_unref_page_prepare+0x62e/0xcb0 mm/page_alloc.c:2348
 free_unref_page_list+0xe3/0xa70 mm/page_alloc.c:2489
 release_pages+0xcd8/0x1380 mm/swap.c:1042
 tlb_batch_pages_flush+0xa8/0x1a0 mm/mmu_gather.c:97
 tlb_flush_mmu_free mm/mmu_gather.c:292 [inline]
 tlb_flush_mmu mm/mmu_gather.c:299 [inline]
 tlb_finish_mmu+0x14b/0x7e0 mm/mmu_gather.c:391
 exit_mmap+0x2cd/0x960 mm/mmap.c:3208
 __mmput+0x128/0x4c0 kernel/fork.c:1347
 mmput+0x60/0x70 kernel/fork.c:1369
 exit_mm kernel/exit.c:567 [inline]
 do_exit+0x9a7/0x29a0 kernel/exit.c:861
 do_group_exit+0xd4/0x2a0 kernel/exit.c:1024
 get_signal+0x249b/0x25f0 kernel/signal.c:2877
 arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:308
 exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
 exit_to_user_mode_prepare+0x11f/0x240 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
 syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:297
 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffffc90012807d00: 00 00 00 00 00 00 f3 f3 f3 f3 00 00 00 00 00 00
 ffffc90012807d80: 00 f1 f1 f1 f1 00 f3 f3 f3 00 00 00 00 00 00 00
>ffffc90012807e00: 00 00 00 00 00 00 f1 f1 f1 f1 f1 f1 04 f2 00 f2
                                     ^
 ffffc90012807e80: f2 f2 00 f3 f3 f3 00 00 00 00 00 00 00 00 00 00
 ffffc90012807f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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