CVE-2024-40955 (GCVE-0-2024-40955)

Vulnerability from cvelistv5 – Published: 2024-07-12 12:31 – Updated: 2026-05-11 20:23
VLAI
Title
ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists()
Summary
In the Linux kernel, the following vulnerability has been resolved: ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists() We can trigger a slab-out-of-bounds with the following commands: mkfs.ext4 -F /dev/$disk 10G mount /dev/$disk /tmp/test echo 2147483647 > /sys/fs/ext4/$disk/mb_group_prealloc echo test > /tmp/test/file && sync ================================================================== BUG: KASAN: slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] Read of size 8 at addr ffff888121b9d0f0 by task kworker/u2:0/11 CPU: 0 PID: 11 Comm: kworker/u2:0 Tainted: GL 6.7.0-next-20240118 #521 Call Trace: dump_stack_lvl+0x2c/0x50 kasan_report+0xb6/0xf0 ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] ext4_mb_regular_allocator+0x19e9/0x2370 [ext4] ext4_mb_new_blocks+0x88a/0x1370 [ext4] ext4_ext_map_blocks+0x14f7/0x2390 [ext4] ext4_map_blocks+0x569/0xea0 [ext4] ext4_do_writepages+0x10f6/0x1bc0 [ext4] [...] ================================================================== The flow of issue triggering is as follows: // Set s_mb_group_prealloc to 2147483647 via sysfs ext4_mb_new_blocks ext4_mb_normalize_request ext4_mb_normalize_group_request ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_mb_group_prealloc ext4_mb_regular_allocator ext4_mb_choose_next_group ext4_mb_choose_next_group_best_avail mb_avg_fragment_size_order order = fls(len) - 2 = 29 ext4_mb_find_good_group_avg_frag_lists frag_list = &sbi->s_mb_avg_fragment_size[order] if (list_empty(frag_list)) // Trigger SOOB! At 4k block size, the length of the s_mb_avg_fragment_size list is 14, but an oversized s_mb_group_prealloc is set, causing slab-out-of-bounds to be triggered by an attempt to access an element at index 29. Add a new attr_id attr_clusters_in_group with values in the range [0, sbi->s_clusters_per_group] and declare mb_group_prealloc as that type to fix the issue. In addition avoid returning an order from mb_avg_fragment_size_order() greater than MB_NUM_ORDERS(sb) and reduce some useless loops.
Severity
No CVSS data available.
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2024-09-10 17:03 UTC
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 7e170922f06bf46effa7c57f6035fc463d6edc7e , < 677ff4589f1501578fa903a25bb14831d0607992 (git)
Affected: 7e170922f06bf46effa7c57f6035fc463d6edc7e , < b829687ae1229224262bcabf49accfa2dbf8db06 (git)
Affected: 7e170922f06bf46effa7c57f6035fc463d6edc7e , < 13df4d44a3aaabe61cd01d277b6ee23ead2a5206 (git)
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Linux Linux Affected: 6.5
Unaffected: 0 , < 6.5 (semver)
Unaffected: 6.6.36 , ≤ 6.6.* (semver)
Unaffected: 6.9.7 , ≤ 6.9.* (semver)
Unaffected: 6.10 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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          "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ext4: arreglar slab-out-of-bounds en ext4_mb_find_good_group_avg_frag_lists() Podemos activar un slab-out-of-bounds con los siguientes comandos: mkfs.ext4 -F /dev/ $disk 10G montaje /dev/$disk /tmp/test echo 2147483647 \u0026gt; /sys/fs/ext4/$disk/mb_group_prealloc echo test \u0026gt; /tmp/test/file \u0026amp;\u0026amp; sync ============ ==================================================== ==== ERROR: KASAN: losa fuera de los l\u00edmites en ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] Lectura de tama\u00f1o 8 en la direcci\u00f3n ffff888121b9d0f0 por tarea kworker/u2:0/11 CPU: 0 PID: 11 Comm: kworker/ u2:0 Tainted: GL 6.7.0-next-20240118 #521 Seguimiento de llamadas: dump_stack_lvl+0x2c/0x50 kasan_report+0xb6/0xf0 ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4_mb_regular_allocator+0x19e9 /0x2370 [ext4] text4_mb_new_blocks+0x88a/0x1370 [ text4] text4_ext_map_blocks+0x14f7/0x2390 [ext4] text4_map_blocks+0x569/0xea0 [ext4] text4_do_writepages+0x10f6/0x1bc0 [ext4] [...] ==================== ================================================ El flujo de La activaci\u00f3n del problema es la siguiente: // Establezca s_mb_group_prealloc en 2147483647 a trav\u00e9s de sysfs ext4_mb_new_blocks ext4_mb_normalize_request ext4_mb_normalize_group_request ac-\u0026gt;ac_g_ex.fe_len = EXT4_SB(sb)-\u0026gt;s_mb_group_prealloc ext4_mb_regular_allocator ext4_mb_choose _next_group ext4_mb_choose_next_group_best_avail mb_avg_fragment_size_order orden = fls(len) - 2 = 29 ext4_mb_find_good_group_avg_frag_lists frag_list = \u0026amp;sbi- \u0026gt;s_mb_avg_fragment_size[order] if (list_empty(frag_list)) // \u00a1Activa SOOB! En un tama\u00f1o de bloque de 4k, la longitud de la lista s_mb_avg_fragment_size es 14, pero se establece un s_mb_group_prealloc de gran tama\u00f1o, lo que provoca que los l\u00edmites de losa se activen al intentar acceder a un elemento en el \u00edndice 29. Agregue un nuevo attr_id attr_clusters_in_group con valores en el rango [0, sbi-\u0026gt;s_clusters_per_group] y declare mb_group_prealloc como ese tipo para solucionar el problema. Adem\u00e1s, evite devolver un pedido de mb_avg_fragment_size_order() mayor que MB_NUM_ORDERS(sb) y reduzca algunos bucles in\u00fatiles."
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists()\n\nWe can trigger a slab-out-of-bounds with the following commands:\n\n    mkfs.ext4 -F /dev/$disk 10G\n    mount /dev/$disk /tmp/test\n    echo 2147483647 \u003e /sys/fs/ext4/$disk/mb_group_prealloc\n    echo test \u003e /tmp/test/file \u0026\u0026 sync\n\n==================================================================\nBUG: KASAN: slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4]\nRead of size 8 at addr ffff888121b9d0f0 by task kworker/u2:0/11\nCPU: 0 PID: 11 Comm: kworker/u2:0 Tainted: GL 6.7.0-next-20240118 #521\nCall Trace:\n dump_stack_lvl+0x2c/0x50\n kasan_report+0xb6/0xf0\n ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4]\n ext4_mb_regular_allocator+0x19e9/0x2370 [ext4]\n ext4_mb_new_blocks+0x88a/0x1370 [ext4]\n ext4_ext_map_blocks+0x14f7/0x2390 [ext4]\n ext4_map_blocks+0x569/0xea0 [ext4]\n ext4_do_writepages+0x10f6/0x1bc0 [ext4]\n[...]\n==================================================================\n\nThe flow of issue triggering is as follows:\n\n// Set s_mb_group_prealloc to 2147483647 via sysfs\next4_mb_new_blocks\n  ext4_mb_normalize_request\n    ext4_mb_normalize_group_request\n      ac-\u003eac_g_ex.fe_len = EXT4_SB(sb)-\u003es_mb_group_prealloc\n  ext4_mb_regular_allocator\n    ext4_mb_choose_next_group\n      ext4_mb_choose_next_group_best_avail\n        mb_avg_fragment_size_order\n          order = fls(len) - 2 = 29\n        ext4_mb_find_good_group_avg_frag_lists\n          frag_list = \u0026sbi-\u003es_mb_avg_fragment_size[order]\n          if (list_empty(frag_list)) // Trigger SOOB!\n\nAt 4k block size, the length of the s_mb_avg_fragment_size list is 14,\nbut an oversized s_mb_group_prealloc is set, causing slab-out-of-bounds\nto be triggered by an attempt to access an element at index 29.\n\nAdd a new attr_id attr_clusters_in_group with values in the range\n[0, sbi-\u003es_clusters_per_group] and declare mb_group_prealloc as\nthat type to fix the issue. In addition avoid returning an order\nfrom mb_avg_fragment_size_order() greater than MB_NUM_ORDERS(sb)\nand reduce some useless loops."
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            "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ext4: arreglar slab-out-of-bounds en ext4_mb_find_good_group_avg_frag_lists() Podemos activar un slab-out-of-bounds con los siguientes comandos: mkfs.ext4 -F /dev/ $disk 10G montaje /dev/$disk /tmp/test echo 2147483647 \u0026gt; /sys/fs/ext4/$disk/mb_group_prealloc echo test \u0026gt; /tmp/test/file \u0026amp;\u0026amp; sync ============ ==================================================== ==== ERROR: KASAN: losa fuera de los l\u00edmites en ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] Lectura de tama\u00f1o 8 en la direcci\u00f3n ffff888121b9d0f0 por tarea kworker/u2:0/11 CPU: 0 PID: 11 Comm: kworker/ u2:0 Tainted: GL 6.7.0-next-20240118 #521 Seguimiento de llamadas: dump_stack_lvl+0x2c/0x50 kasan_report+0xb6/0xf0 ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4_mb_regular_allocator+0x19e9 /0x2370 [ext4] text4_mb_new_blocks+0x88a/0x1370 [ text4] text4_ext_map_blocks+0x14f7/0x2390 [ext4] text4_map_blocks+0x569/0xea0 [ext4] text4_do_writepages+0x10f6/0x1bc0 [ext4] [...] ==================== ================================================ El flujo de La activaci\u00f3n del problema es la siguiente: // Establezca s_mb_group_prealloc en 2147483647 a trav\u00e9s de sysfs ext4_mb_new_blocks ext4_mb_normalize_request ext4_mb_normalize_group_request ac-\u0026gt;ac_g_ex.fe_len = EXT4_SB(sb)-\u0026gt;s_mb_group_prealloc ext4_mb_regular_allocator ext4_mb_choose _next_group ext4_mb_choose_next_group_best_avail mb_avg_fragment_size_order orden = fls(len) - 2 = 29 ext4_mb_find_good_group_avg_frag_lists frag_list = \u0026amp;sbi- \u0026gt;s_mb_avg_fragment_size[order] if (list_empty(frag_list)) // \u00a1Activa SOOB! En un tama\u00f1o de bloque de 4k, la longitud de la lista s_mb_avg_fragment_size es 14, pero se establece un s_mb_group_prealloc de gran tama\u00f1o, lo que provoca que los l\u00edmites de losa se activen al intentar acceder a un elemento en el \u00edndice 29. Agregue un nuevo attr_id attr_clusters_in_group con valores en el rango [0, sbi-\u0026gt;s_clusters_per_group] y declare mb_group_prealloc como ese tipo para solucionar el problema. Adem\u00e1s, evite devolver un pedido de mb_avg_fragment_size_order() mayor que MB_NUM_ORDERS(sb) y reduzca algunos bucles in\u00fatiles."
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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