==================================================================
BUG: KASAN: use-after-free in tcp_retransmit_timer+0x6ee/0x2890 net/ipv4/tcp_timer.c:515
Read of size 8 at addr ffff8880236b36d8 by task rm/18101

CPU: 1 PID: 18101 Comm: rm Not tainted 5.15.106-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 print_address_description+0x63/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0x16b/0x1c0 mm/kasan/report.c:451
 tcp_retransmit_timer+0x6ee/0x2890 net/ipv4/tcp_timer.c:515
 tcp_write_timer_handler+0x1f7/0x9c0 net/ipv4/tcp_timer.c:626
 tcp_write_timer+0x12e/0x280 net/ipv4/tcp_timer.c:646
 call_timer_fn+0x16d/0x560 kernel/time/timer.c:1421
 expire_timers kernel/time/timer.c:1466 [inline]
 __run_timers+0x67c/0x890 kernel/time/timer.c:1737
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1750
 __do_softirq+0x3b3/0x93a kernel/softirq.c:558
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x155/0x240 kernel/softirq.c:636
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:648
 sysvec_apic_timer_interrupt+0x91/0xb0 arch/x86/kernel/apic/apic.c:1097
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:85 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x7b/0x290 mm/kasan/generic.c:189
Code: 00 00 00 00 fc ff df 4f 8d 34 1a 4c 89 f5 4c 29 cd 48 83 fd 10 7f 26 48 85 ed 0f 84 3a 01 00 00 49 f7 d2 49 01 da 41 80 39 00 <0f> 85 c4 01 00 00 49 ff c1 49 ff c2 75 ee e9 1d 01 00 00 45 89 cf
RSP: 0018:ffffc90002eaf6e0 EFLAGS: 00000246
RAX: 0000000000000001 RBX: 1ffff920005d5f06 RCX: ffffffff813833a8
RDX: 0000000000000001 RSI: 0000000000000010 RDI: ffffc90002eaf830
RBP: 0000000000000002 R08: dffffc0000000000 R09: fffff520005d5f07
R10: ffffffffffffffff R11: dffffc0000000001 R12: 1ffffffff1cc4cb7
R13: 1ffffffff1cc4cb7 R14: fffff520005d5f08 R15: ffffc90002eaf7e0
 memset+0x1f/0x40 mm/kasan/shadow.c:44
 unwind_next_frame+0xbc8/0x1fa0 arch/x86/kernel/unwind_orc.c:547
 arch_stack_walk+0x10d/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x113/0x1c0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 __kasan_slab_alloc+0x8e/0xc0 mm/kasan/common.c:467
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x53/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3220 [inline]
 slab_alloc mm/slub.c:3228 [inline]
 kmem_cache_alloc+0xf3/0x280 mm/slub.c:3233
 vm_area_dup+0x1e/0xb0 kernel/fork.c:357
 __split_vma+0xb4/0x4a0 mm/mmap.c:2729
 mprotect_fixup+0x727/0x7d0 mm/mprotect.c:483
 do_mprotect_pkey+0x75b/0xa50 mm/mprotect.c:636
 __do_sys_mprotect mm/mprotect.c:662 [inline]
 __se_sys_mprotect mm/mprotect.c:659 [inline]
 __x64_sys_mprotect+0x7c/0x90 mm/mprotect.c:659
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f1296efa297
Code: 44 00 00 b8 0b 00 00 00 0f 05 48 3d 01 f0 ff ff 73 01 c3 48 8d 0d 21 1f 01 00 f7 d8 89 01 48 83 c8 ff c3 b8 0a 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8d 0d 01 1f 01 00 f7 d8 89 01 48 83
RSP: 002b:00007ffe83100e08 EFLAGS: 00000206 ORIG_RAX: 000000000000000a
RAX: ffffffffffffffda RBX: 00007f1296bb7000 RCX: 00007f1296efa297
RDX: 0000000000000001 RSI: 0000000000001000 RDI: 00007f1296bb5000
RBP: 00007ffe83100f20 R08: 000000000000ffff R09: 00007f1296cddd00
R10: 00007f1296bb5eb8 R11: 0000000000000206 R12: 00007f1296bb7000
R13: 0000000000000007 R14: 0000001700000007 R15: 00007f1296bb25f8
 </TASK>

Allocated by task 12117:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 __kasan_slab_alloc+0x8e/0xc0 mm/kasan/common.c:467
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x53/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3220 [inline]
 slab_alloc mm/slub.c:3228 [inline]
 kmem_cache_alloc+0xf3/0x280 mm/slub.c:3233
 kmem_cache_zalloc include/linux/slab.h:711 [inline]
 net_alloc net/core/net_namespace.c:405 [inline]
 copy_net_ns+0x143/0x5d0 net/core/net_namespace.c:460
 create_new_namespaces+0x425/0x7a0 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0x11e/0x170 kernel/nsproxy.c:226
 ksys_unshare+0x580/0xb20 kernel/fork.c:3094
 __do_sys_unshare kernel/fork.c:3168 [inline]
 __se_sys_unshare kernel/fork.c:3166 [inline]
 __x64_sys_unshare+0x34/0x40 kernel/fork.c:3166
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

The buggy address belongs to the object at ffff8880236b3480
 which belongs to the cache net_namespace of size 6464
The buggy address is located 600 bytes inside of
 6464-byte region [ffff8880236b3480, ffff8880236b4dc0)
The buggy address belongs to the page:
page:ffffea00008dac00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880236b0000 pfn:0x236b0
head:ffffea00008dac00 order:3 compound_mapcount:0 compound_pincount:0
memcg:ffff88801e0d8001
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffffea00008ab200 0000000300000003 ffff888011dc63c0
raw: ffff8880236b0000 0000000080040001 00000001ffffffff ffff88801e0d8001
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5240, ts 105377911211, free_ts 86109762655
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x322a/0x33c0 mm/page_alloc.c:4159
 __alloc_pages+0x272/0x700 mm/page_alloc.c:5421
 alloc_slab_page mm/slub.c:1775 [inline]
 allocate_slab mm/slub.c:1912 [inline]
 new_slab+0xbb/0x4b0 mm/slub.c:1975
 ___slab_alloc+0x6f6/0xe10 mm/slub.c:3008
 __slab_alloc mm/slub.c:3095 [inline]
 slab_alloc_node mm/slub.c:3186 [inline]
 slab_alloc mm/slub.c:3228 [inline]
 kmem_cache_alloc+0x18e/0x280 mm/slub.c:3233
 kmem_cache_zalloc include/linux/slab.h:711 [inline]
 net_alloc net/core/net_namespace.c:405 [inline]
 copy_net_ns+0x143/0x5d0 net/core/net_namespace.c:460
 create_new_namespaces+0x425/0x7a0 kernel/nsproxy.c:110
 copy_namespaces+0x365/0x3b0 kernel/nsproxy.c:178
 copy_process+0x1841/0x3ef0 kernel/fork.c:2201
 kernel_clone+0x210/0x960 kernel/fork.c:2601
 __do_sys_clone kernel/fork.c:2718 [inline]
 __se_sys_clone kernel/fork.c:2702 [inline]
 __x64_sys_clone+0x23f/0x290 kernel/fork.c:2702
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0xc34/0xcf0 mm/page_alloc.c:3317
 free_unref_page+0x95/0x2d0 mm/page_alloc.c:3396
 free_slab mm/slub.c:2015 [inline]
 discard_slab mm/slub.c:2021 [inline]
 __unfreeze_partials+0x1b7/0x210 mm/slub.c:2507
 put_cpu_partial+0x132/0x1a0 mm/slub.c:2587
 do_slab_free mm/slub.c:3487 [inline]
 ___cache_free+0xe3/0x100 mm/slub.c:3506
 qlist_free_all+0x36/0x90 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x162/0x180 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xc0 mm/kasan/common.c:444
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x53/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3220 [inline]
 slab_alloc mm/slub.c:3228 [inline]
 kmem_cache_alloc+0xf3/0x280 mm/slub.c:3233
 getname_flags+0xb8/0x4e0 fs/namei.c:138
 user_path_at_empty+0x2a/0x180 fs/namei.c:2852
 do_readlinkat+0x114/0x3a0 fs/stat.c:442
 __do_sys_readlink fs/stat.c:475 [inline]
 __se_sys_readlink fs/stat.c:472 [inline]
 __x64_sys_readlink+0x7b/0x90 fs/stat.c:472
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Memory state around the buggy address:
 ffff8880236b3580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880236b3600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880236b3680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff8880236b3700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880236b3780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess), 6 bytes skipped:
   0:	df 4f 8d             	fisttps -0x73(%rdi)
   3:	34 1a                	xor    $0x1a,%al
   5:	4c 89 f5             	mov    %r14,%rbp
   8:	4c 29 cd             	sub    %r9,%rbp
   b:	48 83 fd 10          	cmp    $0x10,%rbp
   f:	7f 26                	jg     0x37
  11:	48 85 ed             	test   %rbp,%rbp
  14:	0f 84 3a 01 00 00    	je     0x154
  1a:	49 f7 d2             	not    %r10
  1d:	49 01 da             	add    %rbx,%r10
  20:	41 80 39 00          	cmpb   $0x0,(%r9)
* 24:	0f 85 c4 01 00 00    	jne    0x1ee <-- trapping instruction
  2a:	49 ff c1             	inc    %r9
  2d:	49 ff c2             	inc    %r10
  30:	75 ee                	jne    0x20
  32:	e9 1d 01 00 00       	jmpq   0x154
  37:	45 89 cf             	mov    %r9d,%r15d