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vuln-cve/data/2026/68xxx/CVE-2026-68438.json
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{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2026-68438",
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"state": "PUBLISHED",
"assignerShortName": "Linux",
"dateReserved": "2026-07-30T09:28:09.394Z",
"datePublished": "2026-08-12T00:07:27.105Z",
"dateUpdated": "2026-08-17T05:05:35.262Z"
},
"containers": {
"cna": {
"providerMetadata": {
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux",
"dateUpdated": "2026-08-17T05:05:35.262Z"
},
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmp: Make CSD lock acquisition atomic for debug mode\n\nCommit b0473dcd4b1d (\"smp: Improve smp_call_function_single()\nCSD-lock diagnostics\") changed smp_call_function_single() so that,\nwhen CSD lock debugging is enabled, async !wait calls use the\ndestination CPU csd_data. That improves diagnostics, but it also removes\nthe single-writer property that made the old csd_lock() safe: multiple\nCPUs can now prepare the same destination CPU CSD concurrently.\n\ncsd_lock() currently waits for CSD_FLAG_LOCK to clear and then sets the\nbit with a non-atomic read-modify-write. Two senders can both see an\nunlocked CSD, set the bit, overwrite the callback fields, and enqueue\nthe same llist node. Re-adding a node that is already the queue head can\nmake node->next point to itself, leaving the target CPU stuck walking\ncall_single_queue. Later synchronous work, such as a TLB shootdown, can\nthen remain queued and trigger soft-lockup warnings or panics.\n\nKeep the single csd_lock() implementation, but when CSD lock debugging is\nenabled, acquire CSD_FLAG_LOCK with try_cmpxchg_acquire(). This makes the\ndestination CPU CSD a real atomic lock in the only configuration where it\ncan be shared by multiple remote senders, while preserving the existing\nnon-debug fast path."
}
],
"affected": [
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"kernel/smp.c"
],
"versions": [
{
"version": "b0473dcd4b1d7e2e44947e7ac1820c73a268821a",
"lessThan": "282d220bae5fbfc90cf0e3d5b5e42c00ad79f989",
"status": "affected",
"versionType": "git"
},
{
"version": "b0473dcd4b1d7e2e44947e7ac1820c73a268821a",
"lessThan": "35551efb155e3b83445a6c3f66cb498d5efc182c",
"status": "affected",
"versionType": "git"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"kernel/smp.c"
],
"versions": [
{
"version": "7.1",
"status": "affected"
},
{
"version": "0",
"lessThan": "7.1",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "7.1.6",
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "7.2",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"operator": "OR",
"negate": false,
"cpeMatch": [
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "7.1",
"versionEndExcluding": "7.1.6"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "7.1",
"versionEndExcluding": "7.2"
}
]
}
]
}
],
"references": [
{
"url": "https://git.kernel.org/stable/c/282d220bae5fbfc90cf0e3d5b5e42c00ad79f989"
},
{
"url": "https://git.kernel.org/stable/c/35551efb155e3b83445a6c3f66cb498d5efc182c"
}
],
"title": "smp: Make CSD lock acquisition atomic for debug mode",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
}
}