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CVE-2026-45985— ext4: don't set EXT4_GET_BLOCKS_CONVERT when splitting before submitting I/O

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在分割未写入范围时错误设置EXT4_GET_BLOCKS_CONVERT标志，可能导致数据陈旧问题。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.12% · P2

Possible ATT&CK Techniques 1 AI

T1564 · Hide Artifacts

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux b8a8684502a0fc852afa0056c6bb2a9273f6fcc0< 77e407967cd872cd75d7e4a691908e49c8e6b4d4 affected
b8a8684502a0fc852afa0056c6bb2a9273f6fcc0< 37555690f39f78ef69af347d9aff897e07445949 affected
b8a8684502a0fc852afa0056c6bb2a9273f6fcc0< 67cdb7bd7442bd3cdc6d6088bbb2df9be2fe936c affected
b8a8684502a0fc852afa0056c6bb2a9273f6fcc0< 2920ec61c98b9476781359f05b94da84e80f54d4 affected
b8a8684502a0fc852afa0056c6bb2a9273f6fcc0< 2698731d25823267c29190cb578da9296a0c0d7b affected
b8a8684502a0fc852afa0056c6bb2a9273f6fcc0< 716e7439a5a9b18c3ff882c2f8c834b9ced1aaec affected
b8a8684502a0fc852afa0056c6bb2a9273f6fcc0< feaf2a80e78f89ee8a3464126077ba8683b62791 affected
3.15 affected
… +8 more rows
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I. Basic Information for CVE-2026-45985

Vulnerability Information
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Vulnerability Title
ext4: don't set EXT4_GET_BLOCKS_CONVERT when splitting before submitting I/O
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ext4: don't set EXT4_GET_BLOCKS_CONVERT when splitting before submitting I/O When allocating blocks during within-EOF DIO and writeback with dioread_nolock enabled, EXT4_GET_BLOCKS_PRE_IO was set to split an existing large unwritten extent. However, EXT4_GET_BLOCKS_CONVERT was set when calling ext4_split_convert_extents(), which may potentially result in stale data issues. Assume we have an unwritten extent, and then DIO writes the second half. [UUUUUUUUUUUUUUUU] on-disk extent U: unwritten extent [UUUUUUUUUUUUUUUU] extent status tree |<- ->| ----> dio write this range First, ext4_iomap_alloc() call ext4_map_blocks() with EXT4_GET_BLOCKS_PRE_IO, EXT4_GET_BLOCKS_UNWRIT_EXT and EXT4_GET_BLOCKS_CREATE flags set. ext4_map_blocks() find this extent and call ext4_split_convert_extents() with EXT4_GET_BLOCKS_CONVERT and the above flags set. Then, ext4_split_convert_extents() calls ext4_split_extent() with EXT4_EXT_MAY_ZEROOUT, EXT4_EXT_MARK_UNWRIT2 and EXT4_EXT_DATA_VALID2 flags set, and it calls ext4_split_extent_at() to split the second half with EXT4_EXT_DATA_VALID2, EXT4_EXT_MARK_UNWRIT1, EXT4_EXT_MAY_ZEROOUT and EXT4_EXT_MARK_UNWRIT2 flags set. However, ext4_split_extent_at() failed to insert extent since a temporary lack -ENOSPC. It zeroes out the first half but convert the entire on-disk extent to written since the EXT4_EXT_DATA_VALID2 flag set, but left the second half as unwritten in the extent status tree. [0000000000SSSSSS] data S: stale data, 0: zeroed [WWWWWWWWWWWWWWWW] on-disk extent W: written extent [WWWWWWWWWWUUUUUU] extent status tree Finally, if the DIO failed to write data to the disk, the stale data in the second half will be exposed once the cached extent entry is gone. Fix this issue by not passing EXT4_GET_BLOCKS_CONVERT when splitting an unwritten extent before submitting I/O, and make ext4_split_convert_extents() to zero out the entire extent range to zero for this case, and also mark the extent in the extent status tree for consistency.
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在分割未写入范围时错误设置EXT4_GET_BLOCKS_CONVERT标志，可能导致数据陈旧问题。
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 b8a8684502a0fc852afa0056c6bb2a9273f6fcc0 ~ 77e407967cd872cd75d7e4a691908e49c8e6b4d4 -
Linux Linux 3.15 -

II. Public POCs for CVE-2026-45985

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III. Intelligence Information for CVE-2026-45985

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Patches & Fixes for CVE-2026-45985 (7)

Same Patch Batch · Linux · 2026-05-27 · 275 CVEs total

CVE-2026-45972 9.8 CRITICAL smb: client: fix potential UAF and double free in smb2_open_file()
CVE-2026-45988 9.8 CRITICAL rxrpc: Fix re-decryption of RESPONSE packets
CVE-2026-46039 9.8 CRITICAL rxgk: Fix potential integer overflow in length check
CVE-2026-45898 9.8 CRITICAL RDMA/iwcm: Fix workqueue list corruption by removing work_list
CVE-2026-46043 9.1 CRITICAL RDMA/rxe: Validate pad and ICRC before payload_size() in rxe_rcv
CVE-2026-46056 8.8 HIGH Bluetooth: hci_event: fix potential UAF in SSP passkey handlers
CVE-2026-45945 8.8 HIGH iommu/vt-d: Fix race condition during PASID entry replacement
CVE-2025-71311 8.2 HIGH fs/ntfs3: Initialize new folios before use
CVE-2026-45843 8.2 HIGH slip: bound decode() reads against the compressed packet length
CVE-2026-46037 8.2 HIGH ipv4: icmp: validate reply type before using icmp_pointers
CVE-2026-46099 8.1 HIGH net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels
CVE-2026-46010 8.1 HIGH rxrpc: Fix error handling in rxgk_extract_token()
CVE-2026-46076 7.9 HIGH KVM: nSVM: Raise #UD if unhandled VMMCALL isn't intercepted by L1
CVE-2026-45909 7.8 HIGH clk: mediatek: Drop __initconst from gates
CVE-2026-45935 7.8 HIGH fs/ntfs3: Fix slab-out-of-bounds read in DeleteIndexEntryRoot
CVE-2026-46036 7.8 HIGH vfio/cdx: Serialize VFIO_DEVICE_SET_IRQS with a per-device mutex
CVE-2026-46062 7.8 HIGH ntfs3: fix integer overflow in run_unpack() volume boundary check
CVE-2026-46065 7.8 HIGH fbdev: defio: Disconnect deferred I/O from the lifetime of struct fb_info
CVE-2026-45878 7.8 HIGH drm/amdkfd: Fix watch_id bounds checking in debug address watch v2
CVE-2026-45894 7.8 HIGH iommu/vt-d: Clear Present bit before tearing down PASID entry

Showing top 20 of 275 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-45985

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