In the Linux kernel, the following vulnerability has been resolved: f2fs: fix f2fs_bug_on when uninstalling filesystem call f2fs_evict_inode. creating a large files during checkpoint disable until it runs out of space and then delete it, then remount to enable checkpoint again, and then unmount the filesystem triggers the f2fs_bug_on as below: ------------[ cut here ]------------ kernel BUG at fs/f2fs/inode.c:896! CPU: 2 UID: 0 PID: 1286 Comm: umount Not tainted 6.11.0-rc7-dirty #360 Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI RIP: 0010:f2fs_evict_inode+0x58c/0x610 Call Trace: __die_body+0x15/0x60 die+0x33/0x50 do_trap+0x10a/0x120 f2fs_evict_inode+0x58c/0x610 do_error_trap+0x60/0x80 f2fs_evict_inode+0x58c/0x610 exc_invalid_op+0x53/0x60 f2fs_evict_inode+0x58c/0x610 asm_exc_invalid_op+0x16/0x20 f2fs_evict_inode+0x58c/0x610 evict+0x101/0x260 dispose_list+0x30/0x50 evict_inodes+0x140/0x190 generic_shutdown_super+0x2f/0x150 kill_block_super+0x11/0x40 kill_f2fs_super+0x7d/0x140 deactivate_locked_super+0x2a/0x70 cleanup_mnt+0xb3/0x140 task_work_run+0x61/0x90 The root cause is: creating large files during disable checkpoint period results in not enough free segments, so when writing back root inode will failed in f2fs_enable_checkpoint. When umount the file system after enabling checkpoint, the root inode is dirty in f2fs_evict_inode function, which triggers BUG_ON. The steps to reproduce are as follows: dd if=/dev/zero of=f2fs.img bs=1M count=55 mount f2fs.img f2fs_dir -o checkpoint=disable:10% dd if=/dev/zero of=big bs=1M count=50 sync rm big mount -o remount,checkpoint=enable f2fs_dir umount f2fs_dir Let's redirty inode when there is not free segments during checkpoint is disable.
| Métrique | Valeur | Interprétation |
|---|---|---|
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AV (Vecteur d'Attaque)
Attack Vector
|
Local (L)
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Exploit nécessite un accès local au système |
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AC (Complexité d'Attaque)
Attack Complexity
|
Low (L)
|
Peu de conditions requises pour exploiter |
|
PR (Privilèges Requis)
Privileges Required
|
Low (L)
|
Authentifié avec compte utilisateur basique |
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UI (Interaction Utilisateur)
User Interaction
|
None (N)
|
Aucune interaction utilisateur nécessaire |
|
S (Périmètre)
Scope
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Unchanged (U)
|
Impact reste dans le périmètre du composant compromis |
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C (Impact Confidentialité)
Confidentiality Impact
|
None (N)
|
Aucune divulgation d'informations |
|
I (Impact Intégrité)
Integrity Impact
|
None (N)
|
Aucune modification de données possible |
|
A (Impact Disponibilité)
Availability Impact
|
High (H)
|
Interruption totale du service possible |