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BUG: KASAN: slab-out-of-bounds in compute_postorder+0x802/0xcb0
Write of size 4 at addr ffff888109532518 by task syz.2.803/8020

CPU: 0 UID: 0 PID: 8020 Comm: syz.2.803 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
 compute_postorder+0x802/0xcb0
 bpf_check+0x1f90/0x1d440
 bpf_prog_load+0x1318/0x1930
 __sys_bpf+0x528/0x870
 __x64_sys_bpf+0x7c/0x90
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f23a6d8eba9
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:00007f23a7c2e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f23a6fd5fa0 RCX: 00007f23a6d8eba9
RDX: 0000000000000070 RSI: 0000200000000440 RDI: 0000000000000005
RBP: 00007f23a6e11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f23a6fd6038 R14: 00007f23a6fd5fa0 R15: 00007ffe2bd40fa8
 </TASK>

Allocated by task 8020:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kvmalloc_node_noprof+0x30d/0x5f0
 compute_postorder+0xd6/0xcb0
 bpf_check+0x1f90/0x1d440
 bpf_prog_load+0x1318/0x1930
 __sys_bpf+0x528/0x870
 __x64_sys_bpf+0x7c/0x90
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888109532500
 which belongs to the cache kmalloc-cg-32 of size 32
The buggy address is located 0 bytes to the right of
 allocated 24-byte region [ffff888109532500, ffff888109532518)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888109532ec0 pfn:0x109532
memcg:ffff88811133f401
anon flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000000 ffff88801a449b40 0000000000000000 dead000000000001
raw: ffff888109532ec0 0000000080400017 00000000f5000000 ffff88811133f401
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 26, tgid 26 (kworker/u9:0), ts 11742858490, free_ts 0
 post_alloc_hook+0x240/0x2a0
 get_page_from_freelist+0x21e4/0x22c0
 __alloc_frozen_pages_noprof+0x181/0x370
 alloc_pages_mpol+0x232/0x4a0
 allocate_slab+0x8a/0x370
 ___slab_alloc+0xbeb/0x1410
 __kmalloc_noprof+0x305/0x4f0
 security_prepare_creds+0x52/0x390
 prepare_creds+0x497/0x6c0
 copy_creds+0x106/0xa10
 copy_process+0x964/0x3c00
 kernel_clone+0x21e/0x840
 user_mode_thread+0xdd/0x140
 call_usermodehelper_exec_work+0x5c/0x230
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888109532400: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
 ffff888109532480: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
>ffff888109532500: 00 00 00 fc fc fc fc fc 00 00 00 fc fc fc fc fc
                            ^
 ffff888109532580: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
 ffff888109532600: 00 00 00 fc fc fc fc fc fa fb fb fb fc fc fc fc
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