185 lines
9.8 KiB
JSON
185 lines
9.8 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-45895",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2026-05-13T15:03:33.083Z",
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"datePublished": "2026-05-27T12:17:05.666Z",
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"dateUpdated": "2026-05-27T12:17:05.666Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-05-27T12:17:05.666Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nquota: fix livelock between quotactl and freeze_super\n\nWhen a filesystem is frozen, quotactl_block() enters a retry loop\nwaiting for the filesystem to thaw. It acquires s_umount, checks the\nfreeze state, drops s_umount and uses sb_start_write() - sb_end_write()\npair to wait for the unfreeze.\n\nHowever, this retry loop can trigger a livelock issue, specifically on\nkernels with preemption disabled.\n\nThe mechanism is as follows:\n1. freeze_super() sets SB_FREEZE_WRITE and calls sb_wait_write().\n2. sb_wait_write() calls percpu_down_write(), which initiates\n synchronize_rcu().\n3. Simultaneously, quotactl_block() spins in its retry loop, immediately\n executing the sb_start_write() - sb_end_write() pair.\n4. Because the kernel is non-preemptible and the loop contains no\n scheduling points, quotactl_block() never yields the CPU. This\n prevents that CPU from reaching an RCU quiescent state.\n5. synchronize_rcu() in the freezer thread waits indefinitely for the\n quotactl_block() CPU to report a quiescent state.\n6. quotactl_block() spins indefinitely waiting for the freezer to\n advance, which it cannot do as it is blocked on the RCU sync.\n\nThis results in a hang of the freezer process and 100% CPU usage by the\nquota process.\n\nWhile this can occur intermittently on multi-core systems, it is\nreliably reproducing on a node with the following script, running both\nthe freezer and the quota toggle on the same CPU:\n\n # mkfs.ext4 -O quota /dev/sda 2g && mkdir a_mount\n # mount /dev/sda -o quota,usrquota,grpquota a_mount\n # taskset -c 3 bash -c \"while true; do xfs_freeze -f a_mount; \\\n xfs_freeze -u a_mount; done\" &\n # taskset -c 3 bash -c \"while true; do quotaon a_mount; \\\n quotaoff a_mount; done\" &\n\nAdding cond_resched() to the retry loop fixes the issue. It acts as an\nRCU quiescent state, allowing synchronize_rcu() in percpu_down_write()\nto complete."
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"fs/quota/quota.c"
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],
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"versions": [
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{
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"version": "576215cffdefc1f0ceebffd87abb390926e6b037",
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"lessThan": "37ccd48cf35f3c8b9f2ea961a7b486b91eb71a82",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "576215cffdefc1f0ceebffd87abb390926e6b037",
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"lessThan": "414259caf81a397563fc9baca9c0ef856c4a97cf",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "576215cffdefc1f0ceebffd87abb390926e6b037",
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"lessThan": "02bb1500f1479750e6557c8044f6a2d7e9d30c12",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "576215cffdefc1f0ceebffd87abb390926e6b037",
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"lessThan": "53b2314b26b6640a3657cc924de63a1a8f26ac4d",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "576215cffdefc1f0ceebffd87abb390926e6b037",
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"lessThan": "77449e453dfc006ad738dec55374c4cbc056fd39",
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"status": "affected",
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"versionType": "git"
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"fs/quota/quota.c"
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],
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"versions": [
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{
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"version": "6.5",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "6.5",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.6.128",
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"lessThanOrEqual": "6.6.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.12.75",
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"lessThanOrEqual": "6.12.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.18.14",
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"lessThanOrEqual": "6.18.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.19.4",
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"lessThanOrEqual": "6.19.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.0",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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],
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"cpeApplicability": [
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{
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"nodes": [
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{
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.5",
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"versionEndExcluding": "6.6.128"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.5",
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"versionEndExcluding": "6.12.75"
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.5",
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"versionEndExcluding": "6.18.14"
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.5",
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"versionEndExcluding": "6.19.4"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.5",
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}
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]
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}
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]
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}
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/37ccd48cf35f3c8b9f2ea961a7b486b91eb71a82"
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},
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{
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"url": "https://git.kernel.org/stable/c/414259caf81a397563fc9baca9c0ef856c4a97cf"
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},
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{
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"url": "https://git.kernel.org/stable/c/02bb1500f1479750e6557c8044f6a2d7e9d30c12"
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},
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{
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"url": "https://git.kernel.org/stable/c/53b2314b26b6640a3657cc924de63a1a8f26ac4d"
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},
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{
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"url": "https://git.kernel.org/stable/c/77449e453dfc006ad738dec55374c4cbc056fd39"
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}
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],
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"title": "quota: fix livelock between quotactl and freeze_super",
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"x_generator": {
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"engine": "bippy-1.2.0"
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}
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}
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}
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} |