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BUG: KASAN: slab-use-after-free in rose_timer_expiry+0x471/0x4b0
Read of size 2 at addr ffff888030b4642a by task sshd/5773

CPU: 1 UID: 0 PID: 5773 Comm: sshd Not tainted 6.17.0-rc1-syzkaller-00207-g815957293639 #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:rcu_is_watching+0x55/0xb0
Code: ed bd 8d 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 1c b7 7c 00 48 c7 c3 98 6f a1 92 49 03 1e 48 89 d8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 75 34 8b 03 65 ff 0d 49 e2 f9 10 74 11 83 e0
RSP: 0018:ffffc9000285f1f0 EFLAGS: 00000a06
RAX: 1ffff11026cc65f3 RBX: ffff888136632f98 RCX: 7ec74e8a7932a800
RDX: ffffc9000285f301 RSI: ffffffff8be333e0 RDI: ffffffff8be333a0
RBP: dffffc0000000000 R08: ffffc9000285fee0 R09: 0000000000000000
R10: ffffc9000285f398 R11: fffff5200050be75 R12: ffffc9000285fef0
R13: ffffffff8172c195 R14: ffffffff8dbded18 R15: dffffc0000000000
 lock_release+0x4b/0x3e0
 unwind_next_frame+0x19a9/0x2390
 arch_stack_walk+0x11c/0x150
 stack_trace_save+0x9c/0xe0
 kasan_save_track+0x3e/0x80
 __kasan_slab_alloc+0x6c/0x80
 kmem_cache_alloc_node_noprof+0x1bb/0x3c0
 __alloc_skb+0x112/0x2d0
 tcp_stream_alloc_skb+0x3d/0x340
 tcp_sendmsg_locked+0xf38/0x5620
 tcp_sendmsg+0x2f/0x50
 __sock_sendmsg+0x19c/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: 0033:0x7f7a12365bf2
Code: 89 c7 48 89 44 24 08 e8 7b 34 fa ff 48 8b 44 24 08 48 83 c4 28 c3 c3 64 8b 04 25 18 00 00 00 85 c0 75 20 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 6f 48 8b 15 07 a2 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007fff7422a6c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000000000c4 RCX: 00007f7a12365bf2
RDX: 00000000000000c4 RSI: 000055e278245da0 RDI: 0000000000000004
RBP: 000055e278224b10 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000055e2589d6aa4
R13: 00000000000001e0 R14: 000055e2589d73e8 R15: 00007fff7422a738
 </TASK>

Allocated by task 5594:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_cache_noprof+0x230/0x3d0
 l2tp_tunnel_create+0x92/0x3e0
 pppol2tp_connect+0x7eb/0x1750
 __sys_connect+0x316/0x440
 __x64_sys_connect+0x7a/0x90
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 65:
 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_work+0xed/0x170
 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
 l2tp_session_put+0x12f/0x2b0
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30

Second to last potentially related work creation:
 kasan_save_stack+0x3e/0x60
 kasan_record_aux_stack+0xbd/0xd0
 insert_work+0x3d/0x330
 __queue_work+0xcd2/0xfb0
 queue_work_on+0x181/0x270
 l2tp_udp_encap_destroy+0x2a/0x40
 udpv6_destroy_sock+0x19b/0x270
 sk_common_release+0x75/0x2e0
 inet_release+0x144/0x190
 sock_close+0xc3/0x240
 __fput+0x44c/0xa70
 task_work_run+0x1d4/0x260
 exit_to_user_mode_loop+0xec/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888030b46400
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 42 bytes inside of
 freed 512-byte region [ffff888030b46400, ffff888030b46600)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888030b46400 pfn:0x30b44
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 ffffea0000a68b10 ffffea00008f4610
raw: ffff888030b46400 000000000010000d 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff88801a441c80 ffffea0000a68b10 ffffea00008f4610
head: ffff888030b46400 000000000010000d 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffea0000c2d101 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 5841, tgid 5841 (syz-executor), ts 57024182083, free_ts 57016602729
 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
 addrconf_add_dev+0x24f/0x340
 addrconf_init_auto_addrs+0x57c/0xa30
 addrconf_notify+0xacc/0x1010
 notifier_call_chain+0x1b6/0x3e0
 __dev_notify_flags+0x18d/0x2e0
 netif_change_flags+0xe8/0x1a0
page last free pid 10 tgid 10 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 stack_depot_save_flags+0x436/0x860
 ref_tracker_free+0xfe/0x7d0
 fib_nh_common_release+0x4f/0x420
 free_fib_info_rcu+0xdf/0x310
 rcu_core+0xcab/0x1770
 handle_softirqs+0x286/0x870
 do_softirq+0xec/0x180
 __local_bh_enable_ip+0x17d/0x1c0
 ipv6_get_lladdr+0x2aa/0x3f0
 mld_newpack+0x420/0xc40
 add_grhead+0x5a/0x2a0
 add_grec+0x1452/0x1740
 mld_ifc_work+0x6ed/0xd60
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0

Memory state around the buggy address:
 ffff888030b46300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888030b46380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888030b46400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff888030b46480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888030b46500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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