{"dataType":"CVE_RECORD","dataVersion":"5.1","cveMetadata":{"cveId":"CVE-2024-40955","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2024-07-12T12:17:45.592Z","datePublished":"2024-07-12T12:31:58.328Z","dateUpdated":"2025-05-04T09:18:43.333Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2025-05-04T09:18:43.333Z"},"descriptions":[{"lang":"en","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 > /sys/fs/ext4/$disk/mb_group_prealloc\n    echo test > /tmp/test/file && 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->ac_g_ex.fe_len = EXT4_SB(sb)->s_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 = &sbi->s_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->s_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."}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ext4/mballoc.c","fs/ext4/sysfs.c"],"versions":[{"version":"7e170922f06bf46effa7c57f6035fc463d6edc7e","lessThan":"677ff4589f1501578fa903a25bb14831d0607992","status":"affected","versionType":"git"},{"version":"7e170922f06bf46effa7c57f6035fc463d6edc7e","lessThan":"b829687ae1229224262bcabf49accfa2dbf8db06","status":"affected","versionType":"git"},{"version":"7e170922f06bf46effa7c57f6035fc463d6edc7e","lessThan":"13df4d44a3aaabe61cd01d277b6ee23ead2a5206","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ext4/mballoc.c","fs/ext4/sysfs.c"],"versions":[{"version":"6.5","status":"affected"},{"version":"0","lessThan":"6.5","status":"unaffected","versionType":"semver"},{"version":"6.6.36","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.9.7","lessThanOrEqual":"6.9.*","status":"unaffected","versionType":"semver"},{"version":"6.10","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.5","versionEndExcluding":"6.6.36"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.5","versionEndExcluding":"6.9.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.5","versionEndExcluding":"6.10"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/677ff4589f1501578fa903a25bb14831d0607992"},{"url":"https://git.kernel.org/stable/c/b829687ae1229224262bcabf49accfa2dbf8db06"},{"url":"https://git.kernel.org/stable/c/13df4d44a3aaabe61cd01d277b6ee23ead2a5206"}],"title":"ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists()","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2024-08-02T04:39:55.960Z"},"title":"CVE Program Container","references":[{"url":"https://git.kernel.org/stable/c/677ff4589f1501578fa903a25bb14831d0607992","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/b829687ae1229224262bcabf49accfa2dbf8db06","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/13df4d44a3aaabe61cd01d277b6ee23ead2a5206","tags":["x_transferred"]}]},{"metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2024-40955","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2024-09-10T17:03:45.786138Z"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2024-09-11T17:34:24.264Z"}}]}}