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BUG: KASAN: use-after-free in reiserfs_release_objectid+0x575/0x820 fs/reiserfs/objectid.c:165
Read of size 8188 at addr ffff88804e716050 by task syz.0.30/5993

CPU: 1 PID: 5993 Comm: syz.0.30 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xac/0x220 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x288/0x290 mm/kasan/generic.c:187
 __asan_memmove+0x29/0x70 mm/kasan/shadow.c:94
 reiserfs_release_objectid+0x575/0x820 fs/reiserfs/objectid.c:165
 remove_save_link+0x2ba/0x3c0 fs/reiserfs/super.c:542
 reiserfs_evict_inode+0x395/0x490 fs/reiserfs/inode.c:91
 evict+0x486/0x870 fs/inode.c:705
 __dentry_kill+0x431/0x650 fs/dcache.c:611
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xfe/0x1e0 fs/dcache.c:918
 __fput+0x5e5/0x970 fs/file_table.c:392
 task_work_run+0x1ce/0x250 kernel/task_work.c:239
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f025ed8f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe83d73b88 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f025efe7da0 RCX: 00007f025ed8f749
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f025efe7da0 R08: 0000000000023a9c R09: 0000001583d73e7f
R10: 00000000005d9364 R11: 0000000000000246 R12: 000000000001f5b0
R13: 00007ffe83d73c80 R14: ffffffffffffffff R15: 00007ffe83d73ca0
 </TASK>

The buggy address belongs to the physical page:
page:ffffea000139c580 refcount:2 mapcount:0 mapping:ffff888148c8cd78 index:0x10 pfn:0x4e716
memcg:ffff88801df0c000
aops:def_blk_aops ino:700000
flags: 0xfff5800002822c(referenced|uptodate|lru|workingset|private|mappedtodisk|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff5800002822c ffffea000139c508 ffffea0001645f48 ffff888148c8cd78
raw: 0000000000000010 ffff88823bc50000 00000002ffffffff ffff88801df0c000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x148c48(GFP_NOFS|__GFP_NOFAIL|__GFP_COMP|__GFP_HARDWALL|__GFP_MOVABLE), pid 6000, tgid 5993 (syz.0.30), ts 127028338015, free_ts 127016009737
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
 prep_new_page mm/page_alloc.c:1561 [inline]
 get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
 __alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
 folio_alloc+0x1e/0x30 mm/mempolicy.c:2291
 filemap_alloc_folio+0xdf/0x470 mm/filemap.c:1004
 __filemap_get_folio+0x3ee/0xbc0 mm/filemap.c:1962
 grow_dev_page fs/buffer.c:1058 [inline]
 grow_buffers fs/buffer.c:1118 [inline]
 __getblk_slow fs/buffer.c:1145 [inline]
 __getblk_gfp+0x223/0x660 fs/buffer.c:1439
 __bread_gfp+0x2a/0x330 fs/buffer.c:1473
 sb_bread include/linux/buffer_head.h:326 [inline]
 read_super_block+0x91/0x7c0 fs/reiserfs/super.c:1604
 reiserfs_fill_super+0x7a2/0x2340 fs/reiserfs/super.c:1966
 mount_bdev+0x22b/0x2d0 fs/super.c:1643
 legacy_get_tree+0xea/0x180 fs/fs_context.c:662
 vfs_get_tree+0x8c/0x280 fs/super.c:1764
 do_new_mount+0x24b/0xa40 fs/namespace.c:3386
 do_mount fs/namespace.c:3726 [inline]
 __do_sys_mount fs/namespace.c:3935 [inline]
 __se_sys_mount+0x2da/0x3c0 fs/namespace.c:3912
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1154 [inline]
 free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
 free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2475
 release_pages+0x1fa0/0x2220 mm/swap.c:1022
 __folio_batch_release+0x71/0xe0 mm/swap.c:1042
 folio_batch_release include/linux/pagevec.h:83 [inline]
 shmem_undo_range+0x5d0/0x1a40 mm/shmem.c:1026
 shmem_truncate_range mm/shmem.c:1135 [inline]
 shmem_evict_inode+0x273/0xa70 mm/shmem.c:1264
 evict+0x486/0x870 fs/inode.c:705
 do_unlinkat+0x37b/0x570 fs/namei.c:4406
 __do_sys_unlink fs/namei.c:4447 [inline]
 __se_sys_unlink fs/namei.c:4445 [inline]
 __x64_sys_unlink+0x49/0x50 fs/namei.c:4445
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff88804e716f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88804e716f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88804e717000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88804e717080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88804e717100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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