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BUG: KASAN: use-after-free in filemap_map_pages+0xc95/0x1740
Read of size 8 at addr ffff888036d05000 by task syz.5.62/6394

CPU: 0 UID: 0 PID: 6394 Comm: syz.5.62 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 print_report+0xca/0x240
 kasan_report+0x118/0x150
 filemap_map_pages+0xc95/0x1740
 __handle_mm_fault+0x34ac/0x5440
 handle_mm_fault+0x40a/0x8e0
 __get_user_pages+0x1699/0x2ce0
 populate_vma_page_range+0x29f/0x3a0
 __mm_populate+0x24c/0x380
 vm_mmap_pgoff+0x387/0x4d0
 ksys_mmap_pgoff+0x51f/0x760
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb7d718ebe9
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:00007fb7d804d038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007fb7d73b5fa0 RCX: 00007fb7d718ebe9
RDX: 00000000027ffff7 RSI: 0000000000600000 RDI: 0000200000000000
RBP: 00007fb7d7211e19 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000004012011 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb7d73b6038 R14: 00007fb7d73b5fa0 R15: 00007ffe0f0bbff8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x36d05
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0000d22048 ffffea0000db48c8 0000000000000000
raw: 0000000000000001 ffff88810a7acde0 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x440dc0(GFP_KERNEL_ACCOUNT|__GFP_ZERO|__GFP_COMP), pid 6394, tgid 6392 (syz.5.62), ts 60413321836, free_ts 60423398893
 post_alloc_hook+0x240/0x2a0
 get_page_from_freelist+0x21e4/0x22c0
 __alloc_frozen_pages_noprof+0x181/0x370
 alloc_pages_mpol+0x232/0x4a0
 alloc_pages_noprof+0xa9/0x190
 pte_alloc_one+0x21/0x170
 __handle_mm_fault+0x2795/0x5440
 handle_mm_fault+0x40a/0x8e0
 __get_user_pages+0x1699/0x2ce0
 populate_vma_page_range+0x29f/0x3a0
 __mm_populate+0x24c/0x380
 vm_mmap_pgoff+0x387/0x4d0
 ksys_mmap_pgoff+0x51f/0x760
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 6394 tgid 6392 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 pagetable_dtor_free+0x311/0x3e0
 __handle_mm_fault+0x37dc/0x5440
 handle_mm_fault+0x40a/0x8e0
 __get_user_pages+0x1699/0x2ce0
 populate_vma_page_range+0x29f/0x3a0
 __mm_populate+0x24c/0x380
 vm_mmap_pgoff+0x387/0x4d0
 ksys_mmap_pgoff+0x51f/0x760
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888036d04f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888036d04f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888036d05000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888036d05080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888036d05100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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