REISERFS (device loop4): Using r5 hash to sort names
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BUG: KASAN: use-after-free in strlen+0x58/0x70 lib/string.c:418
Read of size 1 at addr ffff888051fef0c4 by task syz-executor.4/21618

CPU: 1 PID: 21618 Comm: syz-executor.4 Not tainted 6.2.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/21/2023
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:306 [inline]
 print_report+0x163/0x4f0 mm/kasan/report.c:417
 kasan_report+0x13a/0x170 mm/kasan/report.c:517
 strlen+0x58/0x70 lib/string.c:418
 set_de_name_and_namelen fs/reiserfs/namei.c:82 [inline]
 linear_search_in_dir_item fs/reiserfs/namei.c:262 [inline]
 reiserfs_find_entry+0x982/0x19b0 fs/reiserfs/namei.c:331
 reiserfs_lookup+0x1ea/0x4b0 fs/reiserfs/namei.c:368
 __lookup_slow+0x282/0x3e0 fs/namei.c:1685
 lookup_one_len+0x18b/0x2d0 fs/namei.c:2711
 reiserfs_lookup_privroot+0x89/0x1e0 fs/reiserfs/xattr.c:973
 reiserfs_fill_super+0x195b/0x2620 fs/reiserfs/super.c:2192
 mount_bdev+0x271/0x3a0 fs/super.c:1359
 legacy_get_tree+0xef/0x190 fs/fs_context.c:610
 vfs_get_tree+0x8c/0x270 fs/super.c:1489
 do_new_mount+0x28f/0xae0 fs/namespace.c:3145
 do_mount fs/namespace.c:3488 [inline]
 __do_sys_mount fs/namespace.c:3697 [inline]
 __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3674
 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: 0033:0x7fa58ca8d62a
Code: 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d2 e8 b8 04 00 00 0f 1f 84 00 00 00 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa58d7b3f88 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000001120 RCX: 00007fa58ca8d62a
RDX: 00000000200000c0 RSI: 0000000020000040 RDI: 00007fa58d7b3fe0
RBP: 00007fa58d7b4020 R08: 00007fa58d7b4020 R09: 0000000000008001
R10: 0000000000008001 R11: 0000000000000202 R12: 00000000200000c0
R13: 0000000020000040 R14: 00007fa58d7b3fe0 R15: 0000000020000300
 </TASK>

The buggy address belongs to the physical page:
page:ffffea000147fbc0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x51fef
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0000e30c08 ffff8880b9941e20 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 21518, tgid 21517 (syz-executor.0), ts 2265716136990, free_ts 2267726193442
 prep_new_page mm/page_alloc.c:2531 [inline]
 get_page_from_freelist+0x3449/0x35c0 mm/page_alloc.c:4283
 __alloc_pages+0x291/0x7e0 mm/page_alloc.c:5549
 __folio_alloc+0x13/0x30 mm/page_alloc.c:5581
 vma_alloc_folio+0x48a/0x9a0 mm/mempolicy.c:2248
 shmem_alloc_folio mm/shmem.c:1569 [inline]
 shmem_alloc_and_acct_folio+0x596/0xd40 mm/shmem.c:1593
 shmem_get_folio_gfp+0x1408/0x34a0 mm/shmem.c:1920
 shmem_get_folio mm/shmem.c:2051 [inline]
 shmem_write_begin+0x172/0x4f0 mm/shmem.c:2543
 generic_perform_write+0x300/0x5e0 mm/filemap.c:3772
 __generic_file_write_iter+0x17a/0x400 mm/filemap.c:3900
 generic_file_write_iter+0xaf/0x310 mm/filemap.c:3932
 call_write_iter include/linux/fs.h:2189 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x7b2/0xbb0 fs/read_write.c:584
 ksys_write+0x1a0/0x2c0 fs/read_write.c:637
 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:1446 [inline]
 free_pcp_prepare mm/page_alloc.c:1496 [inline]
 free_unref_page_prepare+0xf3a/0x1040 mm/page_alloc.c:3369
 free_unref_page_list+0x6b1/0x950 mm/page_alloc.c:3510
 release_pages+0x219e/0x2470 mm/swap.c:1076
 __pagevec_release+0x84/0x100 mm/swap.c:1096
 pagevec_release include/linux/pagevec.h:71 [inline]
 folio_batch_release include/linux/pagevec.h:135 [inline]
 shmem_undo_range+0x6b6/0x1dd0 mm/shmem.c:947
 shmem_truncate_range mm/shmem.c:1042 [inline]
 shmem_evict_inode+0x258/0x9f0 mm/shmem.c:1151
 evict+0x2a4/0x620 fs/inode.c:664
 __dentry_kill+0x436/0x650 fs/dcache.c:607
 dentry_kill+0xbb/0x290
 dput+0x1d8/0x3f0 fs/dcache.c:913
 __fput+0x5e4/0x890 fs/file_table.c:328
 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:203
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x64/0x2e0 kernel/entry/common.c:296
 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86

Memory state around the buggy address:
 ffff888051feef80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888051fef000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888051fef080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff888051fef100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888051fef180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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