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BUG: KASAN: slab-use-after-free in rose_timer_expiry+0x471/0x4b0
Read of size 2 at addr ffff88810f3ac02a by task syz.2.3557/19988

CPU: 0 UID: 0 PID: 19988 Comm: syz.2.3557 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:console_flush_all+0x7f7/0xc40
Code: 48 21 c3 0f 85 e9 01 00 00 e8 15 49 1f 00 48 8b 5c 24 20 4d 85 f6 75 07 e8 06 49 1f 00 eb 06 e8 ff 48 1f 00 fb 48 8b 44 24 28 <42> 80 3c 20 00 74 08 48 89 df e8 3a b2 82 00 48 8b 1b 48 8b 44 24
RSP: 0018:ffffc90021cc6e00 EFLAGS: 00000287
RAX: 1ffffffff1d367d7 RBX: ffffffff8e9b3eb8 RCX: 0000000000080000
RDX: ffffc90008512000 RSI: 0000000000000da2 RDI: 0000000000000da3
RBP: ffffc90021cc6f50 R08: ffffffff8fa38337 R09: 1ffffffff1f47066
R10: dffffc0000000000 R11: fffffbfff1f47067 R12: dffffc0000000000
R13: 0000000000000001 R14: 0000000000000200 R15: ffffffff8e9b3e60
 console_unlock+0xc4/0x270
 vprintk_emit+0x5b7/0x7a0
 _printk+0xcf/0x120
 __nla_validate_parse+0x1719/0x2d40
 __nla_parse+0x40/0x60
 nfnetlink_rcv+0x31b/0x2520
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 sock_write_iter+0x258/0x330
 vfs_write+0x5c9/0xb30
 ksys_write+0x145/0x250
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc8b218ebe9
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:00007fc8b30ba038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fc8b23b5fa0 RCX: 00007fc8b218ebe9
RDX: 000000000000fe00 RSI: 0000200000000040 RDI: 0000000000000007
RBP: 00007fc8b2211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc8b23b6038 R14: 00007fc8b23b5fa0 R15: 00007ffca02a8718
 </TASK>

Allocated by task 19608:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_cache_noprof+0x230/0x3d0
 __ipv6_dev_mc_inc+0x44f/0xa50
 ipv6_add_dev+0xe54/0x1370
 addrconf_notify+0x794/0x1010
 notifier_call_chain+0x1b6/0x3e0
 register_netdevice+0x1608/0x1ae0
 __ip_tunnel_create+0x3e7/0x560
 ip_tunnel_init_net+0x2ba/0x800
 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 1096:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5b/0x80
 kmem_cache_free_bulk+0x2d1/0x520
 kvfree_rcu_bulk+0xe5/0x1f0
 kfree_rcu_monitor+0x211/0x2a0
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60
 kasan_record_aux_stack+0xbd/0xd0
 kvfree_call_rcu+0xbb/0x410
 ipv6_mc_destroy_dev+0x3c5/0x5a0
 addrconf_ifdown+0x139e/0x1880
 addrconf_notify+0x1bc/0x1010
 notifier_call_chain+0x1b6/0x3e0
 unregister_netdevice_many_notify+0x14d7/0x1ff0
 ops_undo_list+0x3dc/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 ffff88810f3ac000
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 42 bytes inside of
 freed 512-byte region [ffff88810f3ac000, ffff88810f3ac200)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88810f3ac800 pfn:0x10f3ac
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x57ff00000000240(workingset|head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000240 ffff88801a441c80 ffffea0004262210 ffffea0004482110
raw: ffff88810f3ac800 0000000000100001 00000000f5000000 0000000000000000
head: 057ff00000000240 ffff88801a441c80 ffffea0004262210 ffffea0004482110
head: ffff88810f3ac800 0000000000100001 00000000f5000000 0000000000000000
head: 057ff00000000002 ffffea00043ceb01 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 5838, tgid 5838 (syz-executor), ts 45533745484, free_ts 45475929742
 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 5901 tgid 5901 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_noprof+0x1c1/0x3c0
 getname_flags+0xb8/0x540
 user_path_at+0x24/0x60
 __se_sys_chdir+0x91/0x280
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88810f3abf00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88810f3abf80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88810f3ac000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff88810f3ac080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88810f3ac100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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