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CVE-2024-26773

Status: ModifiedMedium (5.5)—

In the Linux kernel, the following vulnerability has been resolved:

ext4: avoid allocating blocks from corrupted group in ext4_mb_try_best_found()

Determine if the group block bitmap is corrupted before using ac_b_ex in ext4_mb_try_best_found() to avoid allocating blocks from a group with a corrupted block bitmap in the following concurrency and making the situation worse.

Technical details traces, logs and code from the original report
ext4_mb_regular_allocator
  ext4_lock_group(sb, group)
  ext4_mb_good_group
   // check if the group bbitmap is corrupted
  ext4_mb_complex_scan_group
   // Scan group gets ac_b_ex but doesn't use it
  ext4_unlock_group(sb, group)
                           ext4_mark_group_bitmap_corrupted(group)
                           // The block bitmap was corrupted during
                           // the group unlock gap.
  ext4_mb_try_best_found
    ext4_lock_group(ac->ac_sb, group)
    ext4_mb_use_best_found
      mb_mark_used
      // Allocating blocks in block bitmap corrupted group

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (2)

CWEs

References

Raw JSON (NVD)

Show
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      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: avoid allocating blocks from corrupted group in ext4_mb_try_best_found()\n\nDetermine if the group block bitmap is corrupted before using ac_b_ex in\next4_mb_try_best_found() to avoid allocating blocks from a group with a\ncorrupted block bitmap in the following concurrency and making the\nsituation worse.\n\next4_mb_regular_allocator\n  ext4_lock_group(sb, group)\n  ext4_mb_good_group\n   // check if the group bbitmap is corrupted\n  ext4_mb_complex_scan_group\n   // Scan group gets ac_b_ex but doesn't use it\n  ext4_unlock_group(sb, group)\n                           ext4_mark_group_bitmap_corrupted(group)\n                           // The block bitmap was corrupted during\n                           // the group unlock gap.\n  ext4_mb_try_best_found\n    ext4_lock_group(ac->ac_sb, group)\n    ext4_mb_use_best_found\n      mb_mark_used\n      // Allocating blocks in block bitmap corrupted group"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se resolvió la siguiente vulnerabilidad: ext4: evite asignar bloques de un grupo dañado en ext4_mb_try_best_found() Determine si el mapa de bits del bloque del grupo está dañado antes de usar ac_b_ex en ext4_mb_try_best_found() para evitar asignar bloques de un grupo con un bloque dañado mapa de bits en la siguiente concurrencia y empeorando la situación. ext4_mb_regular_allocator ext4_lock_group(sb, group) ext4_mb_good_group // verifica si el bbitmap del grupo está dañado ext4_mb_complex_scan_group // El grupo de escaneo obtiene ac_b_ex pero no lo usa ext4_unlock_group(sb, group) ext4_mark_group_bitmap_corrupted(group) // El mapa de bits del bloque se corrompió durante // el grupo desbloquea la brecha. ext4_mb_try_best_found ext4_lock_group(ac->ac_sb, group) ext4_mb_use_best_found mb_mark_used // Asignación de bloques en un grupo dañado de mapa de bits de bloques"
    }
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