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Date:   Tue, 24 Oct 2023 12:08:34 +0200
From:   Jan Kara <jack@suse.cz>
To:     Yikebaer Aizezi <yikebaer61@gmail.com>
Cc:     reiserfs-devel@vger.kernel.org, brauner@kernel.org,
        "dchinner@redhat.com" <dchinner@redhat.com>, jack@suse.cz,
        jlayton@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: KASAN use-after-free Read in search_by_entry_key
Message-ID: <20231024100834.aqwedigye4qa3wfv@quack3>
References: <CALcu4raE3hoh7pLNJBjxWeWv18QOR1XPt4E=XWmdg_b9CN-5Cg@mail.gmail.com>
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Hello!

On Tue 24-10-23 10:30:46, Yikebaer Aizezi wrote:
> When using Healer to fuzz the  Linux 6.6-rc7 Linux kernel,  the following crash
> was triggered.

Thanks for report but I don't think there's a big interest in fixing
reiserfs errors found by a fuzzer. Reiserfs is scheduled for removal from
the kernel so it would be mostly a wasted effort.

								Honza

> 
> HEAD commit: 05d3ef8bba77c1b5f98d941d8b2d4aeab8118ef1 ( Linux 6.6-rc7)
> git tree: upstream
> 
> console output:
> https://drive.google.com/file/d/1qQhQwRydIp1SIiDJghcfp384uZ3gF8-T/view?usp=drive_link
> kernel config:https://drive.google.com/file/d/1gOeRhOnJr2htj6PPnEDTFUkli94JwVvJ/view?usp=drive_link
> C reproducer:https://drive.google.com/file/d/19te0q4_oUfcCoMarjNmkWXvnuwyvhRL-/view?usp=drive_link
> Syzlang reproducer:
> https://drive.google.com/file/d/12vmCNO8HysQ9-C5TC90mpjmZXOJ90k8C/view?usp=drive_link
> 
> If you fix this issue, please add the following tag to the commit:
> Reported-by: Yikebaer Aizezi <yikebaer61@gmail.com>
> 
> ==================================================================
> BUG: KASAN: use-after-free in search_by_entry_key+0x81f/0x960
> fs/reiserfs/namei.c:165
> Read of size 4 at addr ffff8880316dcfc4 by task syz-executor.0/41572
> 
> CPU: 0 PID: 41572 Comm: syz-executor.0 Not tainted 6.6.0-rc7-g05d3ef8bba77 #8
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0xd5/0x150 lib/dump_stack.c:106
>  print_address_description mm/kasan/report.c:364 [inline]
>  print_report+0xc1/0x5e0 mm/kasan/report.c:475
>  kasan_report+0xba/0xf0 mm/kasan/report.c:588
>  bin_search_in_dir_item fs/reiserfs/namei.c:40 [inline]
>  search_by_entry_key+0x81f/0x960 fs/reiserfs/namei.c:165
>  reiserfs_find_entry.part.0+0x139/0xdf0 fs/reiserfs/namei.c:322
>  reiserfs_find_entry fs/reiserfs/namei.c:392 [inline]
>  reiserfs_lookup+0x24d/0x610 fs/reiserfs/namei.c:368
>  __lookup_slow+0x24c/0x460 fs/namei.c:1694
>  lookup_one_len+0x16a/0x1a0 fs/namei.c:2746
>  reiserfs_lookup_privroot+0x92/0x210 fs/reiserfs/xattr.c:977
>  reiserfs_fill_super+0x20fa/0x2ea0 fs/reiserfs/super.c:2174
>  mount_bdev+0x1fd/0x2f0 fs/super.c:1629
>  legacy_get_tree+0x105/0x220 fs/fs_context.c:662
>  vfs_get_tree+0x8d/0x370 fs/super.c:1750
>  do_new_mount fs/namespace.c:3335 [inline]
>  path_mount+0x671/0x1e40 fs/namespace.c:3662
>  do_mount fs/namespace.c:3675 [inline]
>  __do_sys_mount fs/namespace.c:3884 [inline]
>  __se_sys_mount fs/namespace.c:3861 [inline]
>  __x64_sys_mount+0x27f/0x300 fs/namespace.c:3861
>  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+0x63/0xcd
> RIP: 0033:0x7ff4f9690abe
> Code: 48 c7 c0 ff ff ff ff eb aa e8 be 0d 00 00 66 2e 0f 1f 84 00 00
> 00 00 00 0f 1f 40 00 f3 0f 1e fa 49 89 ca b8 a5 00 00 00 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:00007ff4fa3bde38 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 000000000000ffe6 RCX: 00007ff4f9690abe
> RDX: 0000000020010000 RSI: 0000000020010040 RDI: 00007ff4fa3bde90
> RBP: 00007ff4fa3bded0 R08: 00007ff4fa3bded0 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020010000
> R13: 0000000020010040 R14: 00007ff4fa3bde90 R15: 00000000200005c0
>  </TASK>
> 
> The buggy address belongs to the physical page:
> page:ffffea0000c5b700 refcount:0 mapcount:0 mapping:0000000000000000
> index:0x1 pfn:0x316dc
> flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
> page_type: 0xffffffff()
> raw: 00fff00000000000 dead000000000100 dead000000000122 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 41568, tgid 41567
> (syz-executor.2), ts 1584644584471, free_ts 1585399046358
>  prep_new_page mm/page_alloc.c:1543 [inline]
>  get_page_from_freelist+0xf09/0x2c50 mm/page_alloc.c:3170
>  __alloc_pages+0x1c7/0x490 mm/page_alloc.c:4426
>  __folio_alloc+0x12/0x40 mm/page_alloc.c:4458
>  vma_alloc_folio+0x153/0x870 mm/mempolicy.c:2258
>  shmem_alloc_folio+0x121/0x1f0 mm/shmem.c:1658
>  shmem_alloc_and_acct_folio+0xd2/0x150 mm/shmem.c:1683
>  shmem_get_folio_gfp+0x96b/0x18e0 mm/shmem.c:2020
>  shmem_get_folio mm/shmem.c:2143 [inline]
>  shmem_write_begin+0x146/0x440 mm/shmem.c:2688
>  generic_perform_write+0x267/0x5d0 mm/filemap.c:3969
>  shmem_file_write_iter+0x10f/0x140 mm/shmem.c:2865
>  call_write_iter include/linux/fs.h:1956 [inline]
>  new_sync_write fs/read_write.c:491 [inline]
>  vfs_write+0x989/0xdb0 fs/read_write.c:584
>  ksys_write+0x11e/0x240 fs/read_write.c:637
>  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+0x63/0xcd
> page last free stack trace:
>  reset_page_owner include/linux/page_owner.h:24 [inline]
>  free_pages_prepare mm/page_alloc.c:1136 [inline]
>  free_unref_page_prepare+0x450/0xa30 mm/page_alloc.c:2312
>  free_unref_page_list+0xec/0xac0 mm/page_alloc.c:2451
>  release_pages+0xca9/0x1350 mm/swap.c:1042
>  __folio_batch_release+0x73/0xd0 mm/swap.c:1062
>  folio_batch_release include/linux/pagevec.h:83 [inline]
>  shmem_undo_range+0x545/0x10f0 mm/shmem.c:1022
>  shmem_truncate_range mm/shmem.c:1114 [inline]
>  shmem_evict_inode+0x38a/0xb70 mm/shmem.c:1243
>  evict+0x2ed/0x6b0 fs/inode.c:664
>  iput_final fs/inode.c:1775 [inline]
>  iput.part.0+0x50f/0x710 fs/inode.c:1801
>  iput+0x58/0x70 fs/inode.c:1791
>  dentry_unlink_inode+0x28c/0x430 fs/dcache.c:401
>  __dentry_kill+0x3bd/0x640 fs/dcache.c:607
>  dentry_kill fs/dcache.c:733 [inline]
>  dput+0x847/0xde0 fs/dcache.c:913
>  __fput+0x543/0xa70 fs/file_table.c:392
>  task_work_run+0x164/0x250 kernel/task_work.c:180
>  resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
>  exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
>  exit_to_user_mode_prepare+0x215/0x240 kernel/entry/common.c:204
>  __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
>  syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:296
> 
> Memory state around the buggy address:
>  ffff8880316dce80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>  ffff8880316dcf00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> >ffff8880316dcf80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>                                            ^
>  ffff8880316dd000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>  ffff8880316dd080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> ==================================================================
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR