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CVE-2024-42305— ext4: check dot and dotdot of dx_root before making dir indexed

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。目前尚无此漏洞的相关信息，请随时关注CNNVD或厂商公告。

AI Predicted 7.8 Difficulty: Moderate EPSS 0.23% · P13

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux ac27a0ec112a089f1a5102bc8dffc79c8c815571< b80575ffa98b5bb3a5d4d392bfe4c2e03e9557db affected
ac27a0ec112a089f1a5102bc8dffc79c8c815571< 19e13b4d7f0303186fcc891aba8d0de7c8fdbda8 affected
ac27a0ec112a089f1a5102bc8dffc79c8c815571< 42d420517072028fb0eb852c358056b7717ba5aa affected
ac27a0ec112a089f1a5102bc8dffc79c8c815571< 8afe06ed3be7a874b3cd82ef5f8959aca8d6429a affected
ac27a0ec112a089f1a5102bc8dffc79c8c815571< abb411ac991810c0bcbe51c2e76d2502bf611b5c affected
ac27a0ec112a089f1a5102bc8dffc79c8c815571< 9d241b7a39af192d1bb422714a458982c7cc67a2 affected
ac27a0ec112a089f1a5102bc8dffc79c8c815571< cdd345321699042ece4a9d2e70754d2397d378c5 affected
ac27a0ec112a089f1a5102bc8dffc79c8c815571< 50ea741def587a64e08879ce6c6a30131f7111e7 affected
… +10 more rows
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I. Basic Information for CVE-2024-42305

Vulnerability Information
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Vulnerability Title
ext4: check dot and dotdot of dx_root before making dir indexed
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ext4: check dot and dotdot of dx_root before making dir indexed Syzbot reports a issue as follows: ============================================ BUG: unable to handle page fault for address: ffffed11022e24fe PGD 23ffee067 P4D 23ffee067 PUD 0 Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 0 PID: 5079 Comm: syz-executor306 Not tainted 6.10.0-rc5-g55027e689933 #0 Call Trace: <TASK> make_indexed_dir+0xdaf/0x13c0 fs/ext4/namei.c:2341 ext4_add_entry+0x222a/0x25d0 fs/ext4/namei.c:2451 ext4_rename fs/ext4/namei.c:3936 [inline] ext4_rename2+0x26e5/0x4370 fs/ext4/namei.c:4214 [...] ============================================ The immediate cause of this problem is that there is only one valid dentry for the block to be split during do_split, so split==0 results in out of bounds accesses to the map triggering the issue. do_split unsigned split dx_make_map count = 1 split = count/2 = 0; continued = hash2 == map[split - 1].hash; ---> map[4294967295] The maximum length of a filename is 255 and the minimum block size is 1024, so it is always guaranteed that the number of entries is greater than or equal to 2 when do_split() is called. But syzbot's crafted image has no dot and dotdot in dir, and the dentry distribution in dirblock is as follows: bus dentry1 hole dentry2 free |xx--|xx-------------|...............|xx-------------|...............| 0 12 (8+248)=256 268 256 524 (8+256)=264 788 236 1024 So when renaming dentry1 increases its name_len length by 1, neither hole nor free is sufficient to hold the new dentry, and make_indexed_dir() is called. In make_indexed_dir() it is assumed that the first two entries of the dirblock must be dot and dotdot, so bus and dentry1 are left in dx_root because they are treated as dot and dotdot, and only dentry2 is moved to the new leaf block. That's why count is equal to 1. Therefore add the ext4_check_dx_root() helper function to add more sanity checks to dot and dotdot before starting the conversion to avoid the above issue.
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。目前尚无此漏洞的相关信息，请随时关注CNNVD或厂商公告。
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 ac27a0ec112a089f1a5102bc8dffc79c8c815571 ~ b80575ffa98b5bb3a5d4d392bfe4c2e03e9557db -
Linux Linux 2.6.19 -

II. Public POCs for CVE-2024-42305

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III. Intelligence Information for CVE-2024-42305

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Other References for CVE-2024-42305 (8)

Same Patch Batch · Linux · 2024-08-17 · 109 CVEs total

CVE-2024-42285 9.8 CRITICAL RDMA/iwcm: Fix a use-after-free related to destroying CM IDs
CVE-2024-42284 9.1 CRITICAL tipc: Return non-zero value from tipc_udp_addr2str() on error
CVE-2024-43847 8.8 HIGH wifi: ath12k: fix invalid memory access while processing fragmented packets
CVE-2024-43848 8.8 HIGH wifi: mac80211: fix TTLM teardown work
CVE-2024-42287 8.8 HIGH scsi: qla2xxx: Complete command early within lock
CVE-2024-42318 8.8 HIGH landlock: Don't lose track of restrictions on cred_transfer
CVE-2024-42296 7.8 HIGH f2fs: fix return value of f2fs_convert_inline_inode()
CVE-2024-42288 7.8 HIGH scsi: qla2xxx: Fix for possible memory corruption
CVE-2024-43845 7.8 HIGH udf: Fix bogus checksum computation in udf_rename()
CVE-2024-43830 7.8 HIGH leds: trigger: Unregister sysfs attributes before calling deactivate()
CVE-2024-42293 7.8 HIGH arm64: mm: Fix lockless walks with static and dynamic page-table folding
CVE-2024-43832 7.8 HIGH s390/uv: Don't call folio_wait_writeback() without a folio reference
CVE-2024-42301 7.8 HIGH dev/parport: fix the array out-of-bounds risk
CVE-2024-42311 7.8 HIGH hfs: fix to initialize fields of hfs_inode_info after hfs_alloc_inode()
CVE-2024-42313 7.8 HIGH media: venus: fix use after free in vdec_close
CVE-2024-42306 7.8 HIGH udf: Avoid using corrupted block bitmap buffer
CVE-2024-42304 7.8 HIGH ext4: make sure the first directory block is not a hole
CVE-2024-42314 7.8 HIGH btrfs: fix extent map use-after-free when adding pages to compressed bio
CVE-2024-42299 7.8 HIGH fs/ntfs3: Update log->page_{mask,bits} if log->page_size changed
CVE-2024-43840 7.8 HIGH bpf, arm64: Fix trampoline for BPF_TRAMP_F_CALL_ORIG

Showing top 20 of 109 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2024-42305

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