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BUG: KASAN: use-after-free in handle_userfault+0x1364/0x1550 fs/userfaultfd.c:407
BUG: KASAN: use-after-free in handle_userfault+0x1364/0x1550 fs/userfaultfd.c:407
Read of size 8 at addr ffff88807c420190 by task syz-executor.0/26526

CPU: 0 PID: 26526 Comm: syz-executor.0 Not tainted 5.19.0-rc1-next-20220610-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __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
 handle_userfault+0x1364/0x1550 fs/userfaultfd.c:407
 do_anonymous_page mm/memory.c:4134 [inline]
 handle_pte_fault mm/memory.c:4924 [inline]
 __handle_mm_fault+0x40e6/0x4110 mm/memory.c:5065
 handle_mm_fault+0x1c8/0x790 mm/memory.c:5163
 do_user_addr_fault+0x489/0x1250 arch/x86/mm/fault.c:1397
 handle_page_fault arch/x86/mm/fault.c:1488 [inline]
 exc_page_fault+0x9e/0x180 arch/x86/mm/fault.c:1544
 asm_exc_page_fault+0x27/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0033:0x7f3c354255dd
Code: d0 44 0f b6 52 15 49 c1 e2 34 4c 09 d0 44 0f b6 52 13 0f b6 52 11 49 c1 e2 35 48 c1 e2 36 4c 09 d0 48 09 d0 4c 09 c8 4c 09 c0 <48> 89 04 cf 48 89 04 ce c3 66 2e 0f 1f 84 00 00 00 00 00 41 56 66
RSP: 002b:00007f3c3655b5d8 EFLAGS: 00010202
RAX: 00008f0000509120 RBX: 0000000020685000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000020688800 RDI: 0000000020688800
RBP: 0000000020686000 R08: 0000000000009120 R09: 0000000000000000
R10: 0000000000000000 R11: 00007f3c3655bad0 R12: 0000000020686800
R13: 000000000000000f R14: 0000000000000008 R15: 0000000000000001
 </TASK>

Allocated by task 26526:
 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:750 [inline]
 slab_alloc_node mm/slub.c:3214 [inline]
 slab_alloc mm/slub.c:3222 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3229 [inline]
 kmem_cache_alloc+0x142/0x3b0 mm/slub.c:3239
 __do_sys_userfaultfd+0x9b/0x3e0 fs/userfaultfd.c:2098
 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+0x46/0xb0

Freed by task 26525:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track+0x21/0x30 mm/kasan/common.c:45
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free+0x166/0x1a0 mm/kasan/common.c:328
 kasan_slab_free include/linux/kasan.h:200 [inline]
 slab_free_hook mm/slub.c:1727 [inline]
 slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1753
 slab_free mm/slub.c:3507 [inline]
 kmem_cache_free+0xdd/0x5a0 mm/slub.c:3524
 userfaultfd_ctx_put fs/userfaultfd.c:180 [inline]
 userfaultfd_ctx_put+0x312/0x400 fs/userfaultfd.c:168
 userfaultfd_release+0x399/0x670 fs/userfaultfd.c:917
 __fput+0x277/0x9d0 fs/file_table.c:317
 task_work_run+0xdd/0x1a0 kernel/task_work.c:177
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:169 [inline]
 exit_to_user_mode_prepare+0x23c/0x250 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
 syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:294
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

The buggy address belongs to the object at ffff88807c420000
 which belongs to the cache userfaultfd_ctx_cache of size 408
The buggy address is located 400 bytes inside of
 408-byte region [ffff88807c420000, ffff88807c420198)

The buggy address belongs to the physical page:
page:ffffea0001f10800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7c420
head:ffffea0001f10800 order:1 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888145c1dc80
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 26526, tgid 26525 (syz-executor.0), ts 884855765215, free_ts 879804010906
 prep_new_page mm/page_alloc.c:2460 [inline]
 get_page_from_freelist+0xa64/0x3d10 mm/page_alloc.c:4279
 __alloc_pages+0x1c7/0x510 mm/page_alloc.c:5500
 alloc_pages+0x1aa/0x310 mm/mempolicy.c:2279
 alloc_slab_page mm/slub.c:1797 [inline]
 allocate_slab+0x26c/0x3c0 mm/slub.c:1942
 new_slab mm/slub.c:2002 [inline]
 ___slab_alloc+0x985/0xd90 mm/slub.c:3002
 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3089
 slab_alloc_node mm/slub.c:3180 [inline]
 slab_alloc mm/slub.c:3222 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3229 [inline]
 kmem_cache_alloc+0x360/0x3b0 mm/slub.c:3239
 __do_sys_userfaultfd+0x9b/0x3e0 fs/userfaultfd.c:2098
 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+0x46/0xb0
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1375 [inline]
 free_pcp_prepare+0x549/0xd20 mm/page_alloc.c:1425
 free_unref_page_prepare mm/page_alloc.c:3311 [inline]
 free_unref_page+0x19/0x7b0 mm/page_alloc.c:3426
 qlink_free mm/kasan/quarantine.c:168 [inline]
 qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0xa2/0xc0 mm/kasan/common.c:446
 kasan_slab_alloc include/linux/kasan.h:224 [inline]
 slab_post_alloc_hook mm/slab.h:750 [inline]
 slab_alloc_node mm/slub.c:3214 [inline]
 slab_alloc mm/slub.c:3222 [inline]
 __kmalloc+0x200/0x350 mm/slub.c:4413
 kmalloc include/linux/slab.h:605 [inline]
 kzalloc include/linux/slab.h:733 [inline]
 tomoyo_encode2.part.0+0xe9/0x3a0 security/tomoyo/realpath.c:45
 tomoyo_encode2 security/tomoyo/realpath.c:31 [inline]
 tomoyo_encode+0x28/0x50 security/tomoyo/realpath.c:80
 tomoyo_path_perm+0x368/0x400 security/tomoyo/file.c:831
 tomoyo_path_symlink+0x94/0xe0 security/tomoyo/tomoyo.c:199
 security_path_symlink+0xdf/0x150 security/security.c:1182
 do_symlinkat+0x106/0x2e0 fs/namei.c:4365
 __do_sys_symlink fs/namei.c:4392 [inline]
 __se_sys_symlink fs/namei.c:4390 [inline]
 __x64_sys_symlink+0x75/0x90 fs/namei.c:4390
 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+0x46/0xb0

Memory state around the buggy address:
 ffff88807c420080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807c420100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807c420180: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff88807c420200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88807c420280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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