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BUG: KASAN: slab-out-of-bounds in change_page_attr_set_clr+0x625/0xfc0
Read of size 8 at addr ffff8880341fa4e0 by task syz.1.969/8287

CPU: 1 UID: 0 PID: 8287 Comm: syz.1.969 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
 change_page_attr_set_clr+0x625/0xfc0
 _set_pages_array+0x145/0x270
 drm_gem_shmem_get_pages_locked+0x2d0/0x440
 drm_gem_shmem_mmap+0x193/0x460
 drm_gem_mmap_obj+0x18a/0x4e0
 drm_gem_mmap+0x384/0x640
 mmap_region+0x1434/0x1c70
 do_mmap+0xc45/0x10d0
 vm_mmap_pgoff+0x2a6/0x4d0
 ksys_mmap_pgoff+0x51f/0x760
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f107fb8eba9
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:00007f1080afd038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f107fdd5fa0 RCX: 00007f107fb8eba9
RDX: 0000000000000004 RSI: 0000000000004000 RDI: 0000200000001000
RBP: 00007f107fc11e19 R08: 0000000000000003 R09: 0000000100000000
R10: 0000000000000011 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f107fdd6038 R14: 00007f107fdd5fa0 R15: 00007ffc3b912cd8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8880341f3b80 pfn:0x341f0
head: order:4 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f8(unknown)
raw: 00fff00000000040 0000000000000000 dead000000000122 0000000000000000
raw: ffff8880341f3b80 0000000000000000 00000000f8000000 0000000000000000
head: 00fff00000000040 0000000000000000 dead000000000122 0000000000000000
head: ffff8880341f3b80 0000000000000000 00000000f8000000 0000000000000000
head: 00fff00000000004 ffffea0000d07c01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000010
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 4, migratetype Unmovable, gfp_mask 0x428c0(GFP_NOWAIT|__GFP_IO|__GFP_FS|__GFP_COMP), pid 8287, tgid 8286 (syz.1.969), ts 158242774191, free_ts 151593026921
 post_alloc_hook+0x240/0x2a0
 get_page_from_freelist+0x21e4/0x22c0
 __alloc_frozen_pages_noprof+0x181/0x370
 alloc_pages_mpol+0x232/0x4a0
 ___kmalloc_large_node+0x5f/0x1b0
 __kmalloc_large_node_noprof+0x18/0x90
 __kvmalloc_node_noprof+0x6e/0x910
 drm_gem_get_pages+0x166/0xa20
 drm_gem_shmem_get_pages_locked+0x201/0x440
 drm_gem_shmem_mmap+0x193/0x460
 drm_gem_mmap_obj+0x18a/0x4e0
 drm_gem_mmap+0x384/0x640
 mmap_region+0x1434/0x1c70
 do_mmap+0xc45/0x10d0
 vm_mmap_pgoff+0x2a6/0x4d0
 ksys_mmap_pgoff+0x51f/0x760
page last free pid 5845 tgid 5845 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 __put_partials+0x146/0x170
 put_cpu_partial+0x1f2/0x2e0
 __slab_free+0x2b9/0x390
 qlist_free_all+0x97/0x140
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 kmem_cache_alloc_noprof+0x367/0x6e0
 mas_dup_build+0x141/0x1250
 __mt_dup+0x147/0x230
 dup_mmap+0x3bd/0x1ab0
 copy_mm+0x13c/0x4b0
 copy_process+0x1706/0x3c00
 kernel_clone+0x21e/0x840
 __x64_sys_clone+0x18b/0x1e0
 do_syscall_64+0xfa/0xfa0

Memory state around the buggy address:
 ffff8880341fa380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880341fa400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880341fa480: 00 00 00 00 00 00 00 00 00 00 00 00 fe fe fe fe
                                                       ^
 ffff8880341fa500: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
 ffff8880341fa580: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
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