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CVE-2024-40955— ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists()

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于 ext4 文件系统在 ext4_mb_find_good_group_avg_frag_lists 函数中存在越界访问问题。

AI Predicted 7.8 Difficulty: Easy EPSS 0.24% · P14

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 7e170922f06bf46effa7c57f6035fc463d6edc7e< 677ff4589f1501578fa903a25bb14831d0607992 affected
7e170922f06bf46effa7c57f6035fc463d6edc7e< b829687ae1229224262bcabf49accfa2dbf8db06 affected
7e170922f06bf46effa7c57f6035fc463d6edc7e< 13df4d44a3aaabe61cd01d277b6ee23ead2a5206 affected
6.5 affected
< 6.5 unaffected
6.6.36≤ 6.6.* unaffected
6.9.7≤ 6.9.* unaffected
6.10≤ * unaffected
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I. Basic Information for CVE-2024-40955

Vulnerability Information
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Vulnerability Title
ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists()
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于 ext4 文件系统在 ext4_mb_find_good_group_avg_frag_lists 函数中存在越界访问问题。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 7e170922f06bf46effa7c57f6035fc463d6edc7e ~ 677ff4589f1501578fa903a25bb14831d0607992 -
Linux Linux 6.5 -

II. Public POCs for CVE-2024-40955

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III. Intelligence Information for CVE-2024-40955

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Other References for CVE-2024-40955 (3)

Same Patch Batch · Linux · 2024-07-12 · 122 CVEs total

CVE-2024-40937 9.8 CRITICAL gve: Clear napi->skb before dev_kfree_skb_any()
CVE-2024-40907 9.8 CRITICAL ionic: fix kernel panic in XDP_TX action
CVE-2024-40999 9.8 CRITICAL net: ena: Add validation for completion descriptors consistency
CVE-2024-40923 9.8 CRITICAL vmxnet3: disable rx data ring on dma allocation failure
CVE-2024-40983 9.8 CRITICAL tipc: force a dst refcount before doing decryption
CVE-2024-40910 8.8 HIGH ax25: Fix refcount imbalance on inbound connections
CVE-2024-40911 8.8 HIGH wifi: cfg80211: Lock wiphy in cfg80211_get_station
CVE-2024-40941 8.1 HIGH wifi: iwlwifi: mvm: don't read past the mfuart notifcation
CVE-2024-40953 7.9 HIGH KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin()
CVE-2024-40947 7.8 HIGH ima: Avoid blocking in RCU read-side critical section
CVE-2024-39495 7.8 HIGH greybus: Fix use-after-free bug in gb_interface_release due to race condition.
CVE-2024-40909 7.8 HIGH bpf: Fix a potential use-after-free in bpf_link_free()
CVE-2024-40949 7.8 HIGH mm: shmem: fix getting incorrect lruvec when replacing a shmem folio
CVE-2024-40991 7.8 HIGH dmaengine: ti: k3-udma-glue: Fix of_k3_udma_glue_parse_chn_by_id()
CVE-2024-40990 7.8 HIGH RDMA/mlx5: Add check for srq max_sge attribute
CVE-2024-40989 7.8 HIGH KVM: arm64: Disassociate vcpus from redistributor region on teardown
CVE-2024-40925 7.8 HIGH block: fix request.queuelist usage in flush
CVE-2024-40984 7.8 HIGH ACPICA: Revert "ACPICA: avoid Info: mapping multiple BARs. Your kernel is fine."
CVE-2024-40924 7.8 HIGH drm/i915/dpt: Make DPT object unshrinkable
CVE-2024-40970 7.8 HIGH Avoid hw_desc array overrun in dw-axi-dmac

Showing top 20 of 122 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2024-40955

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