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CVE-2026-45895— quota: fix livelock between quotactl and freeze_super

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quota操作与文件系统冻结之间的活锁问题，可能导致系统无响应。

AI Predicted 5.9 Difficulty: Hard EPSS 0.16% · P5

Possible ATT&CK Techniques 1 AI

T1053 · Scheduled Task/Job

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux 576215cffdefc1f0ceebffd87abb390926e6b037< 37ccd48cf35f3c8b9f2ea961a7b486b91eb71a82 affected
576215cffdefc1f0ceebffd87abb390926e6b037< 414259caf81a397563fc9baca9c0ef856c4a97cf affected
576215cffdefc1f0ceebffd87abb390926e6b037< 02bb1500f1479750e6557c8044f6a2d7e9d30c12 affected
576215cffdefc1f0ceebffd87abb390926e6b037< 53b2314b26b6640a3657cc924de63a1a8f26ac4d affected
576215cffdefc1f0ceebffd87abb390926e6b037< 77449e453dfc006ad738dec55374c4cbc056fd39 affected
6.5 affected
< 6.5 unaffected
6.6.128≤ 6.6.* unaffected
… +4 more rows
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I. Basic Information for CVE-2026-45895

Vulnerability Information
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Vulnerability Title
quota: fix livelock between quotactl and freeze_super
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: quota: fix livelock between quotactl and freeze_super When a filesystem is frozen, quotactl_block() enters a retry loop waiting for the filesystem to thaw. It acquires s_umount, checks the freeze state, drops s_umount and uses sb_start_write() - sb_end_write() pair to wait for the unfreeze. However, this retry loop can trigger a livelock issue, specifically on kernels with preemption disabled. The mechanism is as follows: 1. freeze_super() sets SB_FREEZE_WRITE and calls sb_wait_write(). 2. sb_wait_write() calls percpu_down_write(), which initiates synchronize_rcu(). 3. Simultaneously, quotactl_block() spins in its retry loop, immediately executing the sb_start_write() - sb_end_write() pair. 4. Because the kernel is non-preemptible and the loop contains no scheduling points, quotactl_block() never yields the CPU. This prevents that CPU from reaching an RCU quiescent state. 5. synchronize_rcu() in the freezer thread waits indefinitely for the quotactl_block() CPU to report a quiescent state. 6. quotactl_block() spins indefinitely waiting for the freezer to advance, which it cannot do as it is blocked on the RCU sync. This results in a hang of the freezer process and 100% CPU usage by the quota process. While this can occur intermittently on multi-core systems, it is reliably reproducing on a node with the following script, running both the freezer and the quota toggle on the same CPU: # mkfs.ext4 -O quota /dev/sda 2g && mkdir a_mount # mount /dev/sda -o quota,usrquota,grpquota a_mount # taskset -c 3 bash -c "while true; do xfs_freeze -f a_mount; \ xfs_freeze -u a_mount; done" & # taskset -c 3 bash -c "while true; do quotaon a_mount; \ quotaoff a_mount; done" & Adding cond_resched() to the retry loop fixes the issue. It acts as an RCU quiescent state, allowing synchronize_rcu() in percpu_down_write() to complete.
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quota操作与文件系统冻结之间的活锁问题，可能导致系统无响应。
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 576215cffdefc1f0ceebffd87abb390926e6b037 ~ 37ccd48cf35f3c8b9f2ea961a7b486b91eb71a82 -
Linux Linux 6.5 -

II. Public POCs for CVE-2026-45895

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III. Intelligence Information for CVE-2026-45895

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Patches & Fixes for CVE-2026-45895 (3)

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

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-2026-45988 9.8 CRITICAL rxrpc: Fix re-decryption of RESPONSE packets
CVE-2026-45972 9.8 CRITICAL smb: client: fix potential UAF and double free in smb2_open_file()
CVE-2026-46043 9.1 CRITICAL RDMA/rxe: Validate pad and ICRC before payload_size() in rxe_rcv
CVE-2026-45945 8.8 HIGH iommu/vt-d: Fix race condition during PASID entry replacement
CVE-2026-46056 8.8 HIGH Bluetooth: hci_event: fix potential UAF in SSP passkey handlers
CVE-2026-45843 8.2 HIGH slip: bound decode() reads against the compressed packet length
CVE-2025-71311 8.2 HIGH fs/ntfs3: Initialize new folios before use
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-2026-45956 7.8 HIGH drm/exynos: vidi: use priv->vidi_dev for ctx lookup in vidi_connection_ioctl()
CVE-2026-45861 7.8 HIGH gfs2: Fix slab-use-after-free in qd_put
CVE-2026-46036 7.8 HIGH vfio/cdx: Serialize VFIO_DEVICE_SET_IRQS with a per-device mutex
CVE-2026-45959 7.8 HIGH crypto: ccp - Fix a crash due to incorrect cleanup usage of kfree
CVE-2026-45862 7.8 HIGH iommu/vt-d: Flush cache for PASID table before using it
CVE-2026-45894 7.8 HIGH iommu/vt-d: Clear Present bit before tearing down PASID entry
CVE-2026-45935 7.8 HIGH fs/ntfs3: Fix slab-out-of-bounds read in DeleteIndexEntryRoot

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-2026-45895

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