syzbot

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BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:72 [inline]
BUG: KASAN: use-after-free in atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:147 [inline]
BUG: KASAN: use-after-free in tcp_metrics_flush_all+0xd3/0x210 net/ipv4/tcp_metrics.c:909
Read of size 4 at addr ffff88810734b50c by task kworker/u4:7/1374

CPU: 0 PID: 1374 Comm: kworker/u4:7 Tainted: G        W          6.1.141-syzkaller-00038-ge2deb0b42a3a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0xee/0x150 lib/dump_stack.c:106
 print_address_description+0x71/0x210 mm/kasan/report.c:316
 print_report+0x4a/0x60 mm/kasan/report.c:427
 kasan_report+0x122/0x150 mm/kasan/report.c:531
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x280/0x290 mm/kasan/generic.c:189
 __kasan_check_read+0x11/0x20 mm/kasan/shadow.c:31
 instrument_atomic_read include/linux/instrumented.h:72 [inline]
 atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
 refcount_read include/linux/refcount.h:147 [inline]
 tcp_metrics_flush_all+0xd3/0x210 net/ipv4/tcp_metrics.c:909
 tcp_net_metrics_exit_batch+0x10/0x20 net/ipv4/tcp_metrics.c:1037
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x62d/0xb00 net/core/net_namespace.c:604
 process_one_work+0x71f/0xc40 kernel/workqueue.c:2299
 worker_thread+0xa29/0x11f0 kernel/workqueue.c:2446
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Allocated by task 286:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 kasan_save_alloc_info+0x25/0x30 mm/kasan/generic.c:505
 __kasan_slab_alloc+0x72/0x80 mm/kasan/common.c:333
 kasan_slab_alloc include/linux/kasan.h:202 [inline]
 slab_post_alloc_hook+0x4f/0x2d0 mm/slab.h:768
 slab_alloc_node mm/slub.c:3421 [inline]
 slab_alloc mm/slub.c:3431 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3438 [inline]
 kmem_cache_alloc+0x16e/0x330 mm/slub.c:3447
 kmem_cache_zalloc include/linux/slab.h:689 [inline]
 net_alloc net/core/net_namespace.c:413 [inline]
 copy_net_ns+0x145/0x5c0 net/core/net_namespace.c:468
 create_new_namespaces+0x3a2/0x660 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0x120/0x170 kernel/nsproxy.c:226
 ksys_unshare+0x4ac/0x7b0 kernel/fork.c:3388
 __do_sys_unshare kernel/fork.c:3459 [inline]
 __se_sys_unshare kernel/fork.c:3457 [inline]
 __x64_sys_unshare+0x38/0x40 kernel/fork.c:3457
 x64_sys_call+0x767/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:273
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 328:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x31/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x132/0x180 mm/kasan/common.c:241
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:249
 kasan_slab_free include/linux/kasan.h:178 [inline]
 slab_free_hook mm/slub.c:1745 [inline]
 slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1771
 slab_free mm/slub.c:3686 [inline]
 kmem_cache_free+0x12d/0x300 mm/slub.c:3711
 net_free net/core/net_namespace.c:442 [inline]
 cleanup_net+0xa58/0xb00 net/core/net_namespace.c:625
 process_one_work+0x71f/0xc40 kernel/workqueue.c:2299
 worker_thread+0xa29/0x11f0 kernel/workqueue.c:2446
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff88810734b480
 which belongs to the cache net_namespace of size 4224
The buggy address is located 140 bytes inside of
 4224-byte region [ffff88810734b480, ffff88810734c500)

The buggy address belongs to the physical page:
page:ffffea00041cd200 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88810734a300 pfn:0x107348
head:ffffea00041cd200 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 dead000000000122 ffff8881002adb00
raw: ffff88810734a300 0000000080070006 00000001ffffffff 0000000000000000
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 283, tgid 283 (syz-executor), ts 27406984095, free_ts 26153969557
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2637
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2644
 get_page_from_freelist+0x2c7b/0x2cf0 mm/page_alloc.c:4539
 __alloc_pages+0x19e/0x3a0 mm/page_alloc.c:5850
 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
 allocate_slab mm/slub.c:1962 [inline]
 new_slab+0x98/0x3d0 mm/slub.c:2015
 ___slab_alloc+0x6f6/0xb50 mm/slub.c:3203
 __slab_alloc+0x5e/0xa0 mm/slub.c:3302
 slab_alloc_node mm/slub.c:3387 [inline]
 slab_alloc mm/slub.c:3431 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3438 [inline]
 kmem_cache_alloc+0x1b0/0x330 mm/slub.c:3447
 kmem_cache_zalloc include/linux/slab.h:689 [inline]
 net_alloc net/core/net_namespace.c:413 [inline]
 copy_net_ns+0x145/0x5c0 net/core/net_namespace.c:468
 create_new_namespaces+0x3a2/0x660 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0x120/0x170 kernel/nsproxy.c:226
 ksys_unshare+0x4ac/0x7b0 kernel/fork.c:3388
 __do_sys_unshare kernel/fork.c:3459 [inline]
 __se_sys_unshare kernel/fork.c:3457 [inline]
 __x64_sys_unshare+0x38/0x40 kernel/fork.c:3457
 x64_sys_call+0x767/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:273
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1545 [inline]
 free_pcp_prepare mm/page_alloc.c:1619 [inline]
 free_unref_page_prepare+0x742/0x750 mm/page_alloc.c:3581
 free_unref_page+0x8f/0x530 mm/page_alloc.c:3677
 free_the_page mm/page_alloc.c:830 [inline]
 __free_pages+0x67/0x100 mm/page_alloc.c:5939
 __free_slab+0xca/0x1a0 mm/slub.c:2039
 free_slab mm/slub.c:2054 [inline]
 discard_slab mm/slub.c:2060 [inline]
 __unfreeze_partials+0x160/0x190 mm/slub.c:2609
 put_cpu_partial+0xa9/0x100 mm/slub.c:2685
 __slab_free+0x1c4/0x280 mm/slub.c:3563
 do_slab_free mm/slub.c:3640 [inline]
 ___cache_free+0xbf/0xd0 mm/slub.c:3696
 qlink_free mm/kasan/quarantine.c:168 [inline]
 qlist_free_all+0xc6/0x140 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x14a/0x170 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0x24/0x80 mm/kasan/common.c:310
 kasan_slab_alloc include/linux/kasan.h:202 [inline]
 slab_post_alloc_hook+0x4f/0x2d0 mm/slab.h:768
 slab_alloc_node mm/slub.c:3421 [inline]
 slab_alloc mm/slub.c:3431 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3438 [inline]
 kmem_cache_alloc+0x16e/0x330 mm/slub.c:3447
 kmem_cache_zalloc include/linux/slab.h:689 [inline]
 jbd2_alloc_handle include/linux/jbd2.h:1602 [inline]
 new_handle fs/jbd2/transaction.c:476 [inline]
 jbd2__journal_start+0x13d/0x6e0 fs/jbd2/transaction.c:503
 __ext4_journal_start_sb+0x242/0x4a0 fs/ext4/ext4_jbd2.c:105
 __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
 ext4_dirty_inode+0x8f/0x100 fs/ext4/inode.c:6117

Memory state around the buggy address:
 ffff88810734b400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88810734b480: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88810734b500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88810734b580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88810734b600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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