==================================================================
BUG: KASAN: use-after-free in tcp_retransmit_timer+0x2ef3/0x3360 net/ipv4/tcp_timer.c:511
Read of size 8 at addr ffff888077bdd540 by task kworker/u4:7/4393

CPU: 1 PID: 4393 Comm: kworker/u4:7 Not tainted 5.18.0-rc3-syzkaller-01632-gc272e2591169 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_address_description.constprop.0.cold+0xeb/0x495 mm/kasan/report.c:313
 print_report mm/kasan/report.c:429 [inline]
 kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491
 tcp_retransmit_timer+0x2ef3/0x3360 net/ipv4/tcp_timer.c:511
 tcp_write_timer_handler+0x5e6/0xbc0 net/ipv4/tcp_timer.c:622
 tcp_write_timer+0xa2/0x2b0 net/ipv4/tcp_timer.c:642
 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
 expire_timers kernel/time/timer.c:1466 [inline]
 __run_timers.part.0+0x679/0xa80 kernel/time/timer.c:1737
 __run_timers kernel/time/timer.c:1715 [inline]
 run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1750
 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:645
RIP: 0010:check_kcov_mode kernel/kcov.c:166 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x7/0x60 kernel/kcov.c:200
Code: 4b 00 5d be 03 00 00 00 e9 16 be 7e 02 66 0f 1f 44 00 00 48 8b be a8 01 00 00 e8 b4 ff ff ff 31 c0 c3 90 65 8b 05 59 42 89 7e <89> c1 48 8b 34 24 81 e1 00 01 00 00 65 48 8b 14 25 00 70 02 00 a9
RSP: 0000:ffffc90013647c80 EFLAGS: 00000293
RAX: 0000000080000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff890874ce RDI: ffff88805bccbe3c
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff890874c1 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000062
 rcu_lock_release include/linux/rcupdate.h:273 [inline]
 rcu_read_unlock include/linux/rcupdate.h:727 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline]
 batadv_nc_worker+0x858/0xfa0 net/batman-adv/network-coding.c:719
 process_one_work+0x996/0x1610 kernel/workqueue.c:2289
 worker_thread+0x665/0x1080 kernel/workqueue.c:2436
 kthread+0x2e9/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 </TASK>

Allocated by task 3623:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:436 [inline]
 __kasan_slab_alloc+0x90/0xc0 mm/kasan/common.c:469
 kasan_slab_alloc include/linux/kasan.h:224 [inline]
 slab_post_alloc_hook mm/slab.h:749 [inline]
 slab_alloc_node mm/slub.c:3217 [inline]
 slab_alloc mm/slub.c:3225 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3232 [inline]
 kmem_cache_alloc+0x204/0x3b0 mm/slub.c:3242
 kmem_cache_zalloc include/linux/slab.h:704 [inline]
 net_alloc net/core/net_namespace.c:403 [inline]
 copy_net_ns+0x125/0x760 net/core/net_namespace.c:458
 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:226
 ksys_unshare+0x445/0x920 kernel/fork.c:3132
 __do_sys_unshare kernel/fork.c:3203 [inline]
 __se_sys_unshare kernel/fork.c:3201 [inline]
 __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3201
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Last potentially related work creation:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 __kasan_record_aux_stack+0xbe/0xd0 mm/kasan/generic.c:348
 insert_work+0x48/0x350 kernel/workqueue.c:1358
 __queue_work+0x62e/0x1140 kernel/workqueue.c:1517
 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
 expire_timers kernel/time/timer.c:1461 [inline]
 __run_timers.part.0+0x4a3/0xa80 kernel/time/timer.c:1737
 __run_timers kernel/time/timer.c:1715 [inline]
 run_timer_softirq+0x152/0x1d0 kernel/time/timer.c:1752
 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558

Second to last potentially related work creation:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 __kasan_record_aux_stack+0xbe/0xd0 mm/kasan/generic.c:348
 insert_work+0x48/0x350 kernel/workqueue.c:1358
 __queue_work+0x62e/0x1140 kernel/workqueue.c:1517
 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
 expire_timers kernel/time/timer.c:1461 [inline]
 __run_timers.part.0+0x4a3/0xa80 kernel/time/timer.c:1737
 __run_timers kernel/time/timer.c:1715 [inline]
 run_timer_softirq+0x152/0x1d0 kernel/time/timer.c:1752
 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558

The buggy address belongs to the object at ffff888077bdd280
 which belongs to the cache net_namespace of size 6784
The buggy address is located 704 bytes inside of
 6784-byte region [ffff888077bdd280, ffff888077bded00)

The buggy address belongs to the physical page:
page:ffffea0001def600 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888077bdd280 pfn:0x77bd8
head:ffffea0001def600 order:3 compound_mapcount:0 compound_pincount:0
memcg:ffff88806461f1c1
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffffea00010dee08 ffff888010dce288 ffff888010dcd3c0
raw: ffff888077bdd280 0000000000040001 00000001ffffffff ffff88806461f1c1
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 3621, tgid 3621 (syz-executor.1), ts 99347450934, free_ts 99346285092
 prep_new_page mm/page_alloc.c:2441 [inline]
 get_page_from_freelist+0xba2/0x3e00 mm/page_alloc.c:4182
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5408
 alloc_pages+0x1aa/0x310 mm/mempolicy.c:2272
 alloc_slab_page mm/slub.c:1799 [inline]
 allocate_slab+0x26c/0x3c0 mm/slub.c:1944
 new_slab mm/slub.c:2004 [inline]
 ___slab_alloc+0x8df/0xf20 mm/slub.c:3005
 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3092
 slab_alloc_node mm/slub.c:3183 [inline]
 slab_alloc mm/slub.c:3225 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3232 [inline]
 kmem_cache_alloc+0x360/0x3b0 mm/slub.c:3242
 kmem_cache_zalloc include/linux/slab.h:704 [inline]
 net_alloc net/core/net_namespace.c:403 [inline]
 copy_net_ns+0x125/0x760 net/core/net_namespace.c:458
 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:226
 ksys_unshare+0x445/0x920 kernel/fork.c:3132
 __do_sys_unshare kernel/fork.c:3203 [inline]
 __se_sys_unshare kernel/fork.c:3201 [inline]
 __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3201
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1356 [inline]
 free_pcp_prepare+0x549/0xd20 mm/page_alloc.c:1406
 free_unref_page_prepare mm/page_alloc.c:3328 [inline]
 free_unref_page+0x19/0x6a0 mm/page_alloc.c:3423
 skb_free_head+0xac/0x110 net/core/skbuff.c:655
 skb_release_data+0x67a/0x810 net/core/skbuff.c:677
 skb_release_all net/core/skbuff.c:742 [inline]
 __kfree_skb net/core/skbuff.c:756 [inline]
 consume_skb net/core/skbuff.c:915 [inline]
 consume_skb+0xc2/0x160 net/core/skbuff.c:909
 skb_free_datagram+0x1b/0x1f0 net/core/datagram.c:324
 netlink_recvmsg+0x61a/0xea0 net/netlink/af_netlink.c:1999
 sock_recvmsg_nosec net/socket.c:948 [inline]
 sock_recvmsg net/socket.c:966 [inline]
 sock_recvmsg net/socket.c:962 [inline]
 ____sys_recvmsg+0x2be/0x5f0 net/socket.c:2632
 ___sys_recvmsg+0x127/0x200 net/socket.c:2674
 __sys_recvmsg+0xe2/0x1a0 net/socket.c:2704
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Memory state around the buggy address:
 ffff888077bdd400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888077bdd480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888077bdd500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888077bdd580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888077bdd600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
   0:	4b 00 5d be          	rex.WXB add %bl,-0x42(%r13)
   4:	03 00                	add    (%rax),%eax
   6:	00 00                	add    %al,(%rax)
   8:	e9 16 be 7e 02       	jmpq   0x27ebe23
   d:	66 0f 1f 44 00 00    	nopw   0x0(%rax,%rax,1)
  13:	48 8b be a8 01 00 00 	mov    0x1a8(%rsi),%rdi
  1a:	e8 b4 ff ff ff       	callq  0xffffffd3
  1f:	31 c0                	xor    %eax,%eax
  21:	c3                   	retq
  22:	90                   	nop
  23:	65 8b 05 59 42 89 7e 	mov    %gs:0x7e894259(%rip),%eax        # 0x7e894283
* 2a:	89 c1                	mov    %eax,%ecx <-- trapping instruction
  2c:	48 8b 34 24          	mov    (%rsp),%rsi
  30:	81 e1 00 01 00 00    	and    $0x100,%ecx
  36:	65 48 8b 14 25 00 70 	mov    %gs:0x27000,%rdx
  3d:	02 00
  3f:	a9                   	.byte 0xa9