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BUG: KASAN: slab-out-of-bounds in change_page_attr_set_clr+0x625/0xfc0
Read of size 8 at addr ffff888038853ef8 by task syz.8.4398/17746

CPU: 1 UID: 0 PID: 17746 Comm: syz.8.4398 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+0x18b4/0x2110
 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: 0033:0x7f6e8b78ec29
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:00007f6e8c608038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f6e8b9d5fa0 RCX: 00007f6e8b78ec29
RDX: 0000000000000004 RSI: 0000000000004000 RDI: 0000200000001000
RBP: 00007f6e8b811e41 R08: 0000000000000003 R09: 0000000100000000
R10: 0000000000000011 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6e8b9d6038 R14: 00007f6e8b9d5fa0 R15: 00007ffea00f8d28
 </TASK>

Allocated by task 17746:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kvmalloc_node_noprof+0x5cd/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+0x18b4/0x2110
 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

The buggy address belongs to the object at ffff888038853e00
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 0 bytes to the right of
 allocated 248-byte region [ffff888038853e00, ffff888038853ef8)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x38852
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801ac41b40 ffffea0000e44a00 dead000000000006
raw: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801ac41b40 ffffea0000e44a00 dead000000000006
head: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000
head: 00fff00000000001 ffffea0000e21481 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5856, tgid 5856 (syz-executor), ts 66434175966, free_ts 0
 post_alloc_hook+0x240/0x2a0
 get_page_from_freelist+0x2365/0x2440
 __alloc_frozen_pages_noprof+0x181/0x370
 alloc_pages_mpol+0x232/0x4a0
 allocate_slab+0x96/0x3a0
 ___slab_alloc+0xe94/0x1920
 __slab_alloc+0x65/0x100
 __kmalloc_noprof+0x471/0x7f0
 fib_create_info+0x172d/0x3210
 fib_table_insert+0xc6/0x1b50
 fib_magic+0x2c4/0x390
 fib_add_ifaddr+0x144/0x5f0
 fib_netdev_event+0x382/0x490
 notifier_call_chain+0x1b6/0x3e0
 __dev_notify_flags+0x18d/0x2e0
 netif_change_flags+0xe8/0x1a0
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888038853d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888038853e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888038853e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc
                                                                ^
 ffff888038853f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888038853f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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