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BUG: KASAN: slab-use-after-free in rose_timer_expiry+0x471/0x4b0
Read of size 2 at addr ffff8880243eb42a by task syz.0.7252/22764

CPU: 0 UID: 0 PID: 22764 Comm: syz.0.7252 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:check_preemption_disabled+0x5/0x120
Code: 48 c7 c6 e0 32 e3 8b eb 1c 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57 41 56 <53> 48 83 ec 10 65 48 8b 05 be ce 26 07 48 89 44 24 08 65 8b 05 c6
RSP: 0018:ffffc900064d72d8 EFLAGS: 00000282
RAX: 0000000000000001 RBX: ffffffff8184623c RCX: ffff88810a529cc0
RDX: 0000000000000000 RSI: ffffffff8be332e0 RDI: ffffffff8be332a0
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffffff8172c195
R10: ffffc900064d7438 R11: ffffffff81ac3910 R12: 1ffff92000c9ae7d
R13: ffffc900064d7420 R14: ffffc900064d73e8 R15: ffffffff8172c195
 rcu_is_watching+0x15/0xb0
 unwind_next_frame+0xd4/0x2390
 arch_stack_walk+0x11c/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
 __put_anon_vma+0x12b/0x2d0
 unlink_anon_vmas+0x503/0x670
 free_pgtables+0x72b/0x9c0
 exit_mmap+0x444/0xb50
 __mmput+0x118/0x420
 exit_mm+0x1da/0x2c0
 do_exit+0x648/0x2300
 do_group_exit+0x21c/0x2d0
 __x64_sys_exit_group+0x3f/0x40
 x64_sys_call+0x21f7/0x2200
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7efd6e38ebe9
Code: Unable to access opcode bytes at 0x7efd6e38ebbf.
RSP: 002b:00007ffc6552a7d8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007efd6e38ebe9
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffc6552a83c R08: 000000026552a8cf R09: 00000000000927c0
R10: 0000000000000001 R11: 0000000000000246 R12: 000000000000092a
R13: 00000000000927c0 R14: 00000000000574be R15: 00007ffc6552a890
 </TASK>

Allocated by task 22486:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_cache_noprof+0x230/0x3d0
 cfmuxl_create+0x4c/0x1c0
 cfcnfg_create+0x79/0x380
 caif_init_net+0x81/0xc0
 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 5861:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5b/0x80
 kfree+0x18e/0x440
 cfcnfg_remove+0x5e/0xa0
 caif_exit_net+0x480/0x4a0
 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 ffff8880243eb400
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 42 bytes inside of
 freed 512-byte region [ffff8880243eb400, ffff8880243eb600)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8880243e9800 pfn:0x243e8
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff88801a441c80 ffffea0000c40a10 ffffea0000c1d910
raw: ffff8880243e9800 000000000010000e 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff88801a441c80 ffffea0000c40a10 ffffea0000c1d910
head: ffff8880243e9800 000000000010000e 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffea000090fa01 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5844, tgid 5844 (syz-executor), ts 66980098579, free_ts 66826369463
 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
 fib6_info_alloc+0x30/0xf0
 ip6_route_info_create+0x142/0x860
 ip6_route_add+0x49/0x1b0
 inet6_addr_add+0x6b2/0xc00
 inet6_rtm_newaddr+0x93d/0xd20
 rtnetlink_rcv_msg+0x7cf/0xb70
 netlink_rcv_skb+0x208/0x470
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
page last free pid 5844 tgid 5844 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 __slab_free+0x303/0x3c0
 qlist_free_all+0x97/0x140
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 __kmalloc_cache_noprof+0x1be/0x3d0
 netdevice_event+0x3a1/0x8a0
 notifier_call_chain+0x1b6/0x3e0
 call_netdevice_notifiers+0x88/0xc0
 vlan_dev_open+0x213/0x5e0
 __dev_open+0x470/0x880
 __dev_change_flags+0x1ea/0x6d0
 netif_change_flags+0x88/0x1a0
 dev_change_flags+0x130/0x260
 vlan_device_event+0x1bc2/0x1ef0
 notifier_call_chain+0x1b6/0x3e0

Memory state around the buggy address:
 ffff8880243eb300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880243eb380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880243eb400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff8880243eb480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880243eb500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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