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BUG: KASAN: use-after-free in user_mode arch/x86/include/asm/ptrace.h:131 [inline]
BUG: KASAN: use-after-free in trace_page_fault_entries arch/x86/mm/fault.c:1541 [inline]
BUG: KASAN: use-after-free in do_page_fault+0x66/0x330 arch/x86/mm/fault.c:1553
Read of size 8 at addr ffff8881ce75fe40 by task syz-executor.3/16585

CPU: 1 PID: 16585 Comm: syz-executor.3 Tainted: G        W         5.4.268-syzkaller-00012-g51cf29fc2bfc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:

The buggy address belongs to the page:
page:ffffea000739d7c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x8000000000000000()
raw: 8000000000000000 0000000000000000 ffffea000739d7c8 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
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)
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook mm/page_alloc.c:2165 [inline]
 prep_new_page+0x18f/0x370 mm/page_alloc.c:2171
 get_page_from_freelist+0x2d13/0x2d90 mm/page_alloc.c:3794
 __alloc_pages_nodemask+0x393/0x840 mm/page_alloc.c:4891
 alloc_slab_page+0x39/0x3c0 mm/slub.c:343
 allocate_slab mm/slub.c:1683 [inline]
 new_slab+0x97/0x440 mm/slub.c:1749
 new_slab_objects mm/slub.c:2505 [inline]
 ___slab_alloc+0x2fe/0x490 mm/slub.c:2667
 __slab_alloc+0x62/0xa0 mm/slub.c:2707
 slab_alloc_node mm/slub.c:2792 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 kmem_cache_alloc+0x109/0x250 mm/slub.c:2842
 getname_flags+0xb8/0x4e0 fs/namei.c:141
 getname fs/namei.c:212 [inline]
 user_path_mountpoint_at+0x22/0x40 fs/namei.c:2842
 ksys_umount+0x143/0x410 fs/namespace.c:1690
 __do_sys_umount fs/namespace.c:1716 [inline]
 __se_sys_umount fs/namespace.c:1714 [inline]
 __x64_sys_umount+0x56/0x60 fs/namespace.c:1714
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1176 [inline]
 __free_pages_ok+0x847/0x950 mm/page_alloc.c:1438
 free_the_page mm/page_alloc.c:4953 [inline]
 __free_pages+0x91/0x140 mm/page_alloc.c:4959
 __free_slab+0x221/0x2e0 mm/slub.c:1774
 free_slab mm/slub.c:1789 [inline]
 discard_slab mm/slub.c:1795 [inline]
 unfreeze_partials+0x14e/0x180 mm/slub.c:2288
 put_cpu_partial+0x44/0x180 mm/slub.c:2324
 __slab_free+0x297/0x360 mm/slub.c:2971
 qlist_free_all+0x43/0xb0 mm/kasan/quarantine.c:167
 quarantine_reduce+0x1d9/0x210 mm/kasan/quarantine.c:260
 __kasan_kmalloc+0x41/0x210 mm/kasan/common.c:507
 slab_post_alloc_hook mm/slab.h:584 [inline]
 slab_alloc_node mm/slub.c:2829 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 kmem_cache_alloc+0xd9/0x250 mm/slub.c:2842
 kmem_cache_alloc_node include/linux/slab.h:427 [inline]
 __alloc_skb+0x7a/0x4d0 net/core/skbuff.c:198
 alloc_skb include/linux/skbuff.h:1080 [inline]
 nlmsg_new include/net/netlink.h:888 [inline]
 inet6_netconf_notify_devconf+0xc9/0x180 net/ipv6/addrconf.c:573
 __addrconf_sysctl_unregister net/ipv6/addrconf.c:6979 [inline]
 addrconf_sysctl_unregister net/ipv6/addrconf.c:7003 [inline]
 addrconf_ifdown+0x17cc/0x1a90 net/ipv6/addrconf.c:3910
 addrconf_notify+0x375/0xe50 net/ipv6/addrconf.c:3681
 notifier_call_chain kernel/notifier.c:98 [inline]
 __raw_notifier_call_chain kernel/notifier.c:399 [inline]
 raw_notifier_call_chain+0x95/0x110 kernel/notifier.c:406
 call_netdevice_notifiers_info net/core/dev.c:1670 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:1682 [inline]
 call_netdevice_notifiers net/core/dev.c:1696 [inline]
 rollback_registered_many+0xce5/0x1330 net/core/dev.c:8631

Memory state around the buggy address:
 ffff8881ce75fd00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881ce75fd80: ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00
>ffff8881ce75fe00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff8881ce75fe80: ff ff ff ff f1 f1 f1 f1 00 f2 f2 f2 04 f3 f3 f3
 ffff8881ce75ff00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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