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BUG: KASAN: slab-use-after-free in rose_timer_expiry+0x471/0x4b0
Read of size 2 at addr ffff88804901682a by task syz.0.9627/10823

CPU: 0 UID: 0 PID: 10823 Comm: syz.0.9627 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:notifier_call_chain+0x90/0x3e0
Code: 86 c2 31 00 45 31 ed e9 4d 03 00 00 48 8b 04 24 48 c1 e8 03 48 89 44 24 18 49 8d 7c 24 08 48 89 f8 48 c1 e8 03 42 80 3c 30 00 <74> 05 e8 29 2e 95 00 49 8b 44 24 08 48 89 44 24 08 4d 89 e7 49 c1
RSP: 0018:ffffc9000676ec78 EFLAGS: 00000246
RAX: 1ffffffff1eb099d RBX: dffffc0000000000 RCX: 0000000000080000
RDX: ffffc900035d1000 RSI: 0000000000006025 RDI: ffffffff8f584ce8
RBP: 00000000ffffffd1 R08: ffff888047b0d640 R09: 0000000000000006
R10: 000000000000000b R11: 0000000000000002 R12: ffffffff8f584ce0
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffffffff1eadb64
 register_netdevice+0x121c/0x1ae0
 br_dev_newlink+0x6a/0x140
 rtnl_newlink_create+0x310/0xb00
 rtnl_newlink+0x16d6/0x1c70
 rtnetlink_rcv_msg+0x7cf/0xb70
 netlink_rcv_skb+0x208/0x470
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 ____sys_sendmsg+0x505/0x830
 ___sys_sendmsg+0x21f/0x2a0
 __x64_sys_sendmsg+0x19b/0x260
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7efd33d8ebe9
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:00007efd31ff6038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007efd33fc5fa0 RCX: 00007efd33d8ebe9
RDX: 0000000000000000 RSI: 0000200000000000 RDI: 0000000000000007
RBP: 00007efd33e11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007efd33fc6038 R14: 00007efd33fc5fa0 R15: 00007ffc5a1140b8
 </TASK>

Allocated by task 10544:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_cache_noprof+0x230/0x3d0
 fib6_net_init+0x3a5/0x8f0
 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 10544:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5b/0x80
 kfree+0x18e/0x440
 fib6_net_exit+0x26c/0x300
 ops_undo_list+0x49a/0x990
 setup_net+0x2d3/0x320
 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

The buggy address belongs to the object at ffff888049016800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 42 bytes inside of
 freed 512-byte region [ffff888049016800, ffff888049016a00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888049015000 pfn:0x49014
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 ffffea0000daeb10 ffff88801a4407c8
raw: ffff888049015000 000000000010000b 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff88801a441c80 ffffea0000daeb10 ffff88801a4407c8
head: ffff888049015000 000000000010000b 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffea0001240501 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 32422, tgid 32419 (syz.1.6856), ts 447623781306, free_ts 446770925072
 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
 device_add+0xbe/0xb50
 add_one_compat_dev+0x3af/0x5c0
 rdma_dev_init_net+0x1dd/0x270
 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
page last free pid 32384 tgid 32384 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
 kmem_cache_alloc_noprof+0x1c1/0x3c0
 vm_area_alloc+0x24/0x140
 do_brk_flags+0x33c/0xbb0
 __se_sys_brk+0x9bb/0xb90
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888049016700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888049016780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888049016800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff888049016880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888049016900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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