CVE-2026-90181 (GCVE-0-2026-90181)
Vulnerability from cvelistv5
Published
2026-09-17 16:07
Modified
2026-10-19 08:59
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
ublk: avoid teardown retry loop on xarray allocation failure
__ublk_shmem_remove_ranges() removes matching maple tree ranges in
batches, but first stores each range into a temporary xarray so that the
pages can be unpinned after dropping the maple tree lock.
That temporary xarray is filled under the maple tree lock with
xa_store(..., GFP_ATOMIC). If the store fails before mas_erase(), the
current range is left in the tree and the helper returns false. The
outer ublk_shmem_remove_ranges() loop then immediately retries the same
range. While the atomic allocation keeps failing, the teardown path has
no forward progress.
The issue can be reproduced with radix_tree_node failslab injection after
a SHMEM_ZC buffer has already been registered:
# Kernel config:
# CONFIG_BLK_DEV_UBLK=y
# CONFIG_DEBUG_FS=y
# CONFIG_FAULT_INJECTION=y
# CONFIG_FAULT_INJECTION_DEBUG_FS=y
# CONFIG_FAILSLAB=y
echo 10 > /proc/sys/vm/nr_hugepages
mkdir -p /tmp/htlb
mount -t hugetlbfs none /tmp/htlb
fallocate -l 4M /tmp/htlb/ublk_buf
dev_id=$(kublk add -t null --shmem_zc \
--htlb /tmp/htlb/ublk_buf |
awk -F '[ :]' '/dev id/ {print $3}')
echo 1 > /sys/kernel/slab/radix_tree_node/failslab
echo Y > /sys/kernel/debug/failslab/cache-filter
echo Y > /sys/kernel/debug/failslab/ignore-gfp-wait
echo 1 > /sys/kernel/debug/failslab/interval
echo -1 > /sys/kernel/debug/failslab/times
echo 100 > /sys/kernel/debug/failslab/probability
kublk del -n "$dev_id"
On the unfixed kernel the delete command was still running after 3
seconds. Disabling failslab made it return. The fault-injection stack
showed:
should_failslab
kmem_cache_alloc_lru_noprof
__xas_nomem
__xa_store
xa_store
__ublk_shmem_remove_ranges
ublk_cdev_rel
ublk_ctrl_del_dev
Remove the allocation from the teardown loop. Keep the existing batch
limit, but collect {base_pfn, nr_pages} pairs in a fixed-size stack array.
Once a matching range is found, the range is erased from the maple tree
before dropping the lock, so each successful scan makes progress without
depending on any GFP_ATOMIC allocation.
With the same failslab settings, the fixed kernel completed
"kublk del -n $dev_id" successfully in about 45 ms.
References
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"drivers/block/ublk_drv.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "b9cc6cc74daf6fef533dbe65d8cee779fea69600",
"status": "affected",
"version": "309e02dccf64e1b7bd2067abedc270e33b0aadf3",
"versionType": "git"
},
{
"lessThan": "4fd66a7f829f3f38f92a79081f0f2688aed644f0",
"status": "affected",
"version": "309e02dccf64e1b7bd2067abedc270e33b0aadf3",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"drivers/block/ublk_drv.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "7.1"
},
{
"lessThan": "7.1",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.6",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2.6",
"versionStartIncluding": "7.1",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.3",
"versionStartIncluding": "7.1",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nublk: avoid teardown retry loop on xarray allocation failure\n\n__ublk_shmem_remove_ranges() removes matching maple tree ranges in\nbatches, but first stores each range into a temporary xarray so that the\npages can be unpinned after dropping the maple tree lock.\n\nThat temporary xarray is filled under the maple tree lock with\nxa_store(..., GFP_ATOMIC). If the store fails before mas_erase(), the\ncurrent range is left in the tree and the helper returns false. The\nouter ublk_shmem_remove_ranges() loop then immediately retries the same\nrange. While the atomic allocation keeps failing, the teardown path has\nno forward progress.\n\nThe issue can be reproduced with radix_tree_node failslab injection after\na SHMEM_ZC buffer has already been registered:\n\n # Kernel config:\n # CONFIG_BLK_DEV_UBLK=y\n # CONFIG_DEBUG_FS=y\n # CONFIG_FAULT_INJECTION=y\n # CONFIG_FAULT_INJECTION_DEBUG_FS=y\n # CONFIG_FAILSLAB=y\n\n echo 10 \u003e /proc/sys/vm/nr_hugepages\n mkdir -p /tmp/htlb\n mount -t hugetlbfs none /tmp/htlb\n fallocate -l 4M /tmp/htlb/ublk_buf\n\n dev_id=$(kublk add -t null --shmem_zc \\\n\t\t--htlb /tmp/htlb/ublk_buf |\n\t awk -F \u0027[ :]\u0027 \u0027/dev id/ {print $3}\u0027)\n\n echo 1 \u003e /sys/kernel/slab/radix_tree_node/failslab\n echo Y \u003e /sys/kernel/debug/failslab/cache-filter\n echo Y \u003e /sys/kernel/debug/failslab/ignore-gfp-wait\n echo 1 \u003e /sys/kernel/debug/failslab/interval\n echo -1 \u003e /sys/kernel/debug/failslab/times\n echo 100 \u003e /sys/kernel/debug/failslab/probability\n\n kublk del -n \"$dev_id\"\n\nOn the unfixed kernel the delete command was still running after 3\nseconds. Disabling failslab made it return. The fault-injection stack\nshowed:\n\n should_failslab\n kmem_cache_alloc_lru_noprof\n __xas_nomem\n __xa_store\n xa_store\n __ublk_shmem_remove_ranges\n ublk_cdev_rel\n ublk_ctrl_del_dev\n\nRemove the allocation from the teardown loop. Keep the existing batch\nlimit, but collect {base_pfn, nr_pages} pairs in a fixed-size stack array.\nOnce a matching range is found, the range is erased from the maple tree\nbefore dropping the lock, so each successful scan makes progress without\ndepending on any GFP_ATOMIC allocation.\n\nWith the same failslab settings, the fixed kernel completed\n\"kublk del -n $dev_id\" successfully in about 45 ms."
}
],
"providerMetadata": {
"dateUpdated": "2026-10-19T08:59:18.253Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/b9cc6cc74daf6fef533dbe65d8cee779fea69600"
},
{
"url": "https://git.kernel.org/stable/c/4fd66a7f829f3f38f92a79081f0f2688aed644f0"
}
],
"title": "ublk: avoid teardown retry loop on xarray allocation failure",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-90181",
"datePublished": "2026-09-17T16:07:05.725Z",
"dateReserved": "2026-09-11T19:38:34.791Z",
"dateUpdated": "2026-10-19T08:59:18.253Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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