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CVE-2025-38434— Revert "riscv: Define TASK_SIZE_MAX for __access_ok()"

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riscv架构中TASK_SIZE_MAX定义不当，可能导致无效地址访问。

CVSS 7.8 · High EPSS 0.19% · P8

Possible ATT&CK Techniques 1 AI

T1200.003

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux ad5643cf2f699989daa85d909403febd6712fccb< fe30c30bf3bb68d4a4d8c7c814769857b5c973e6 affected
ad5643cf2f699989daa85d909403febd6712fccb< f8b1898748dfeb4f9b67b6a6d661f354b9de3523 affected
ad5643cf2f699989daa85d909403febd6712fccb< 890ba5be6335dbbbc99af14ea007befb5f83f174 affected
6.10 affected
< 6.10 unaffected
6.12.36≤ 6.12.* unaffected
6.15.5≤ 6.15.* unaffected
6.16≤ * unaffected
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I. Basic Information for CVE-2025-38434

Vulnerability Information
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Vulnerability Title
Revert "riscv: Define TASK_SIZE_MAX for __access_ok()"
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: Revert "riscv: Define TASK_SIZE_MAX for __access_ok()" This reverts commit ad5643cf2f69 ("riscv: Define TASK_SIZE_MAX for __access_ok()"). This commit changes TASK_SIZE_MAX to be LONG_MAX to optimize access_ok(), because the previous TASK_SIZE_MAX (default to TASK_SIZE) requires some computation. The reasoning was that all user addresses are less than LONG_MAX, and all kernel addresses are greater than LONG_MAX. Therefore access_ok() can filter kernel addresses. Addresses between TASK_SIZE and LONG_MAX are not valid user addresses, but access_ok() let them pass. That was thought to be okay, because they are not valid addresses at hardware level. Unfortunately, one case is missed: get_user_pages_fast() happily accepts addresses between TASK_SIZE and LONG_MAX. futex(), for instance, uses get_user_pages_fast(). This causes the problem reported by Robert [1]. Therefore, revert this commit. TASK_SIZE_MAX is changed to the default: TASK_SIZE. This unfortunately reduces performance, because TASK_SIZE is more expensive to compute compared to LONG_MAX. But correctness first, we can think about optimization later, if required.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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riscv架构中TASK_SIZE_MAX定义不当，可能导致无效地址访问。
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 ad5643cf2f699989daa85d909403febd6712fccb ~ fe30c30bf3bb68d4a4d8c7c814769857b5c973e6 -
Linux Linux 6.10 -

II. Public POCs for CVE-2025-38434

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III. Intelligence Information for CVE-2025-38434

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Same Patch Batch · Linux · 2025-07-25 · 114 CVEs total

CVE-2025-38429 10.0 CRITICAL bus: mhi: ep: Update read pointer only after buffer is written
CVE-2025-38411 9.8 CRITICAL netfs: Fix double put of request
CVE-2025-38430 9.8 CRITICAL nfsd: nfsd4_spo_must_allow() must check this is a v4 compound request
CVE-2025-38439 9.8 CRITICAL bnxt_en: Set DMA unmap len correctly for XDP_REDIRECT
CVE-2025-38365 9.1 CRITICAL btrfs: fix a race between renames and directory logging
CVE-2025-38377 8.8 HIGH rose: fix dangling neighbour pointers in rose_rt_device_down()
CVE-2025-38367 8.8 HIGH LoongArch: KVM: Avoid overflow with array index
CVE-2025-38437 8.8 HIGH ksmbd: fix potential use-after-free in oplock/lease break ack
CVE-2025-38375 8.4 HIGH virtio-net: ensure the received length does not exceed allocated size
CVE-2025-38395 8.4 HIGH regulator: gpio: Fix the out-of-bounds access to drvdata::gpiods
CVE-2025-38386 7.8 HIGH ACPICA: Refuse to evaluate a method if arguments are missing
CVE-2025-38422 7.8 HIGH net: lan743x: Modify the EEPROM and OTP size for PCI1xxxx devices
CVE-2025-38435 7.8 HIGH riscv: vector: Fix context save/restore with xtheadvector
CVE-2025-38449 7.8 HIGH drm/gem: Acquire references on GEM handles for framebuffers
CVE-2025-38382 7.8 HIGH btrfs: fix iteration of extrefs during log replay
CVE-2025-38412 7.8 HIGH platform/x86: dell-wmi-sysman: Fix WMI data block retrieval in sysfs callbacks
CVE-2025-38398 7.8 HIGH spi: spi-qpic-snand: reallocate BAM transactions
CVE-2025-38440 7.8 HIGH net/mlx5e: Fix race between DIM disable and net_dim()
CVE-2025-38396 7.8 HIGH fs: export anon_inode_make_secure_inode() and fix secretmem LSM bypass
CVE-2025-38447 7.8 HIGH mm/rmap: fix potential out-of-bounds page table access during batched unmap

Showing top 20 of 114 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-38434

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