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BUG: KASAN: slab-use-after-free in afs_dynroot_test_super+0x56/0xc0 fs/afs/super.c:434
Read of size 8 at addr ffff888017bf2000 by task syz-executor.1/10267

CPU: 0 PID: 10267 Comm: syz-executor.1 Not tainted 6.5.0-syzkaller-01207-g1c59d383390f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0x163/0x540 mm/kasan/report.c:475
 kasan_report+0x175/0x1b0 mm/kasan/report.c:588
 afs_dynroot_test_super+0x56/0xc0 fs/afs/super.c:434
 sget_fc+0x145/0x750 fs/super.c:778
 afs_get_tree+0x39c/0x1120 fs/afs/super.c:577
 vfs_get_tree+0x8c/0x280 fs/super.c:1711
 do_new_mount+0x28f/0xae0 fs/namespace.c:3335
 do_mount fs/namespace.c:3675 [inline]
 __do_sys_mount fs/namespace.c:3884 [inline]
 __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3861
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f241807cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2418e320c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f241819bf80 RCX: 00007f241807cae9
RDX: 0000000020000140 RSI: 0000000020000100 RDI: 0000000000000000
RBP: 00007f24180c847a R08: 0000000020000380 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f241819bf80 R15: 00007fff8080be28
 </TASK>

Allocated by task 10266:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383
 kmalloc include/linux/slab.h:582 [inline]
 kzalloc include/linux/slab.h:703 [inline]
 afs_alloc_sbi fs/afs/super.c:509 [inline]
 afs_get_tree+0xbb/0x1120 fs/afs/super.c:571
 vfs_get_tree+0x8c/0x280 fs/super.c:1711
 do_new_mount+0x28f/0xae0 fs/namespace.c:3335
 do_mount fs/namespace.c:3675 [inline]
 __do_sys_mount fs/namespace.c:3884 [inline]
 __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3861
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 5062:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522
 ____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:162 [inline]
 slab_free_hook mm/slub.c:1792 [inline]
 slab_free_freelist_hook mm/slub.c:1818 [inline]
 slab_free mm/slub.c:3801 [inline]
 __kmem_cache_free+0x25f/0x3b0 mm/slub.c:3814
 deactivate_locked_super+0xa5/0x200 fs/super.c:454
 cleanup_mnt+0x426/0x4c0 fs/namespace.c:1254
 task_work_run+0x24a/0x300 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xd9/0x100 kernel/entry/common.c:171
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x64/0x280 kernel/entry/common.c:296
 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff888017bf2000
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
 freed 32-byte region [ffff888017bf2000, ffff888017bf2020)

The buggy address belongs to the physical page:
page:ffffea00005efc80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x17bf2
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000200 ffff888012841500 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080400040 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 10266, tgid 10262 (syz-executor.4), ts 377376889845, free_ts 377318430940
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1570
 prep_new_page mm/page_alloc.c:1577 [inline]
 get_page_from_freelist+0x31e8/0x3370 mm/page_alloc.c:3221
 __alloc_pages+0x255/0x670 mm/page_alloc.c:4477
 alloc_slab_page+0x6a/0x160 mm/slub.c:1862
 allocate_slab mm/slub.c:2009 [inline]
 new_slab+0x84/0x2f0 mm/slub.c:2062
 ___slab_alloc+0xade/0x1100 mm/slub.c:3215
 __slab_alloc mm/slub.c:3314 [inline]
 __slab_alloc_node mm/slub.c:3367 [inline]
 slab_alloc_node mm/slub.c:3460 [inline]
 __kmem_cache_alloc_node+0x1af/0x270 mm/slub.c:3509
 kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1076
 kmalloc include/linux/slab.h:582 [inline]
 kzalloc include/linux/slab.h:703 [inline]
 afs_alloc_sbi fs/afs/super.c:509 [inline]
 afs_get_tree+0xbb/0x1120 fs/afs/super.c:571
 vfs_get_tree+0x8c/0x280 fs/super.c:1711
 do_new_mount+0x28f/0xae0 fs/namespace.c:3335
 do_mount fs/namespace.c:3675 [inline]
 __do_sys_mount fs/namespace.c:3884 [inline]
 __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3861
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1161 [inline]
 free_unref_page_prepare+0x903/0xa30 mm/page_alloc.c:2348
 free_unref_page_list+0x596/0x830 mm/page_alloc.c:2489
 release_pages+0x2193/0x2470 mm/swap.c:1042
 tlb_batch_pages_flush mm/mmu_gather.c:97 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:292 [inline]
 tlb_flush_mmu+0x100/0x210 mm/mmu_gather.c:299
 tlb_finish_mmu+0xd4/0x1f0 mm/mmu_gather.c:391
 exit_mmap+0x3e2/0xad0 mm/mmap.c:3215
 __mmput+0x115/0x3c0 kernel/fork.c:1356
 exit_mm+0x21f/0x300 kernel/exit.c:567
 do_exit+0x612/0x2290 kernel/exit.c:861
 do_group_exit+0x206/0x2c0 kernel/exit.c:1024
 get_signal+0x1709/0x17e0 kernel/signal.c:2881
 arch_do_signal_or_restart+0x91/0x670 arch/x86/kernel/signal.c:308
 exit_to_user_mode_loop+0x6a/0x100 kernel/entry/common.c:168
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x64/0x280 kernel/entry/common.c:296
 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86

Memory state around the buggy address:
 ffff888017bf1f00: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
 ffff888017bf1f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888017bf2000: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
                   ^
 ffff888017bf2080: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
 ffff888017bf2100: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
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