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BUG: KASAN: use-after-free in rose_timer_expiry+0x471/0x4b0
Read of size 2 at addr ffff88811af49c2a by task syz.0.9311/27298

CPU: 1 UID: 0 PID: 27298 Comm: syz.0.9311 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:
 <IRQ>
 dump_stack_lvl+0x189/0x250
 print_report+0xca/0x240
 kasan_report+0x118/0x150
 rose_timer_expiry+0x471/0x4b0
 call_timer_fn+0x17e/0x5f0
 __run_timer_base+0x61a/0x860
 run_timer_softirq+0xb7/0x180
 handle_softirqs+0x286/0x870
 __irq_exit_rcu+0xca/0x1f0
 irq_exit_rcu+0x9/0x30
 sysvec_apic_timer_interrupt+0xa6/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:kasan_check_range+0x9f/0x2c0
Code: 00 fc ff df 4d 8d 34 19 4d 89 f4 4d 29 dc 49 83 fc 10 7f 29 4d 85 e4 0f 84 41 01 00 00 4c 89 cb 48 f7 d3 4c 01 fb 41 80 3b 00 <0f> 85 de 01 00 00 49 ff c3 48 ff c3 75 ee e9 21 01 00 00 44 89 dd
RSP: 0018:ffffc900082cf318 EFLAGS: 00000246
RAX: 1ffffffff3365501 RBX: ffffffffffffffff RCX: ffffffff822e41d4
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88801ccf7f2c
RBP: ffff88801ccf7ee0 R08: ffff88801ccf7f2f R09: 1ffff1100399efe5
R10: dffffc0000000000 R11: ffffed100399efe5 R12: 0000000000000001
R13: 0000000000000001 R14: ffffed100399efe6 R15: 1ffff1100399efe5
 page_table_check_clear+0x334/0x700
 unmap_page_range+0x3460/0x4370
 unmap_vmas+0x399/0x580
 exit_mmap+0x248/0xb50
 __mmput+0x118/0x420
 exit_mm+0x1da/0x2c0
 do_exit+0x648/0x2300
 do_group_exit+0x21c/0x2d0
 get_signal+0x1286/0x1340
 arch_do_signal_or_restart+0x9a/0x750
 exit_to_user_mode_loop+0x75/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1dd978ebe9
Code: Unable to access opcode bytes at 0x7f1dd978ebbf.
RSP: 002b:00007f1dda5ed0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f1dd99b5fa8 RCX: 00007f1dd978ebe9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f1dd99b5fa8
RBP: 00007f1dd99b5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1dd99b6038 R14: 00007ffccf477d40 R15: 00007ffccf477e28
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffffffffffffffff pfn:0x11af49
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff00000000000 0000000000000000 00000000ffffffff 0000000000000000
raw: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 25096, tgid 25095 (syz.0.8352), ts 290989119165, free_ts 295194958798
 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_cache_noprof+0x296/0x3d0
 __genradix_ptr_alloc+0x352/0x4a0
 __genradix_prealloc+0x44/0x90
 sctp_stream_init+0x14b/0x440
 sctp_association_new+0x10dd/0x25f0
 sctp_connect_new_asoc+0x2c5/0x690
 sctp_sendmsg+0x155c/0x2810
 __sock_sendmsg+0x19c/0x270
 __sys_sendto+0x3bd/0x520
 __x64_sys_sendto+0xde/0x100
page last free pid 5842 tgid 5842 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 __put_partials+0x156/0x1a0
 put_cpu_partial+0x17c/0x250
 __slab_free+0x2d5/0x3c0
 qlist_free_all+0x97/0x140
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 kmem_cache_alloc_lru_noprof+0x1c6/0x3d0
 shmem_alloc_inode+0x28/0x40
 alloc_inode+0x6a/0x1b0
 new_inode+0x22/0x170
 shmem_get_inode+0x346/0xe90
 shmem_mknod+0x18c/0x3e0
 shmem_mkdir+0x33/0x70
 vfs_mkdir+0x306/0x510
 do_mkdirat+0x247/0x590

Memory state around the buggy address:
 ffff88811af49b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88811af49b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88811af49c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                  ^
 ffff88811af49c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88811af49d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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