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BUG: KASAN: slab-use-after-free in rose_timer_expiry+0x471/0x4b0
Read of size 2 at addr ffff88810b80ac2a by task syz.0.11677/12418

CPU: 0 UID: 0 PID: 12418 Comm: syz.0.11677 Not tainted 6.16.0-syzkaller-06600-g1dbf1d590d10 #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:unwind_next_frame+0x171c/0x2390
Code: 47 0c 01 0f 85 18 02 00 00 80 3d be 6d 2d 11 00 0f 85 0b 02 00 00 c6 05 b1 6d 2d 11 01 4c 89 f7 e8 89 0c 00 00 e9 f7 01 00 00 <48> 8b 54 24 08 48 8d 5a 02 48 83 c2 03 48 89 d8 48 c1 e8 03 0f b6
RSP: 0018:ffffc9000258f278 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffc9000258f3e0 RCX: 0000000000000000
RDX: ffffffff902f99fc RSI: 0000000000000001 RDI: ffffc9000258f408
RBP: dffffc0000000000 R08: ffffc9000258f407 R09: 0000000000000000
R10: ffffc9000258f3f8 R11: fffff520004b1e81 R12: ffffc9000258f3a8
R13: ffffc9000258f3f8 R14: ffffc9000258f3a8 R15: 1ffffffff205f33f
 __unwind_start+0x5b9/0x760
 arch_stack_walk+0xe4/0x150
 stack_trace_save+0x9c/0xe0
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_cache_noprof+0x230/0x3d0
 kmem_cache_free+0x166/0x400
 exit_mmap+0x53f/0xb50
 __mmput+0x118/0x420
 exit_mm+0x1da/0x2c0
 do_exit+0x648/0x22e0
 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: 0033:0x7f16f0d8ebe9
Code: Unable to access opcode bytes at 0x7f16f0d8ebbf.
RSP: 002b:00007f16f1cb30e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f16f0fb6098 RCX: 00007f16f0d8ebe9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f16f0fb6098
RBP: 00007f16f0fb6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f16f0fb6128 R14: 00007ffd8e9929a0 R15: 00007ffd8e992a88
 </TASK>

Allocated by task 12213:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_cache_noprof+0x230/0x3d0
 rpc_mkpipe_data+0x59/0x390
 nfs4blocklayout_net_init+0x85/0x1b0
 ops_init+0x35c/0x5c0
 setup_net+0x10c/0x320
 copy_net_ns+0x31b/0x4d0
 create_new_namespaces+0x3f3/0x720
 unshare_nsproxy_namespaces+0x11c/0x170
 ksys_unshare+0x4c8/0x8c0
 __x64_sys_unshare+0x38/0x50
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 424:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x62/0x70
 kfree+0x18e/0x440
 nfs4blocklayout_net_exit+0xa0/0x100
 ops_undo_list+0x49a/0x990
 cleanup_net+0x4c5/0x800
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30

The buggy address belongs to the object at ffff88810b80ac00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 42 bytes inside of
 freed 512-byte region [ffff88810b80ac00, ffff88810b80ae00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10b808
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff88801a441c80 ffffea00049ee100 dead000000000002
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 057ff00000000040 ffff88801a441c80 ffffea00049ee100 dead000000000002
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 057ff00000000002 ffffea00042e0201 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5830, tgid 5830 (syz-executor), ts 66782597496, free_ts 66717252790
 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/0x3b0
 ___slab_alloc+0xbfc/0x1480
 __kmalloc_noprof+0x305/0x4f0
 fib6_info_alloc+0x30/0xf0
 ip6_route_info_create+0x142/0x860
 addrconf_f6i_alloc+0x1d2/0x450
 addrconf_permanent_addr+0x274/0x9d0
 addrconf_notify+0x887/0x1010
 notifier_call_chain+0x1b6/0x3e0
 __dev_notify_flags+0x18d/0x2e0
 netif_change_flags+0xe8/0x1a0
 do_setlink+0xc55/0x41c0
page last free pid 5261 tgid 5261 stack trace:
 __free_frozen_pages+0xc71/0xe70
 __put_partials+0x161/0x1c0
 put_cpu_partial+0x17c/0x250
 __slab_free+0x2f7/0x400
 qlist_free_all+0x97/0x140
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 kmem_cache_alloc_node_noprof+0x1bb/0x3c0
 __alloc_skb+0x112/0x2d0
 alloc_skb_with_frags+0xca/0x890
 sock_alloc_send_pskb+0x857/0x990
 unix_dgram_sendmsg+0x461/0x1850
 __sock_sendmsg+0x21c/0x270
 __sys_sendto+0x3bd/0x520
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0xfa/0x3b0

Memory state around the buggy address:
 ffff88810b80ab00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88810b80ab80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88810b80ac00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff88810b80ac80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88810b80ad00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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