CVE-2022-49266 (GCVE-0-2022-49266)
Vulnerability from cvelistv5
Published
2025-02-26 01:56
Modified
2025-08-28 14:42
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
block: fix rq-qos breakage from skipping rq_qos_done_bio()
a647a524a467 ("block: don't call rq_qos_ops->done_bio if the bio isn't
tracked") made bio_endio() skip rq_qos_done_bio() if BIO_TRACKED is not set.
While this fixed a potential oops, it also broke blk-iocost by skipping the
done_bio callback for merged bios.
Before, whether a bio goes through rq_qos_throttle() or rq_qos_merge(),
rq_qos_done_bio() would be called on the bio on completion with BIO_TRACKED
distinguishing the former from the latter. rq_qos_done_bio() is not called
for bios which wenth through rq_qos_merge(). This royally confuses
blk-iocost as the merged bios never finish and are considered perpetually
in-flight.
One reliably reproducible failure mode is an intermediate cgroup geting
stuck active preventing its children from being activated due to the
leaf-only rule, leading to loss of control. The following is from
resctl-bench protection scenario which emulates isolating a web server like
workload from a memory bomb run on an iocost configuration which should
yield a reasonable level of protection.
# cat /sys/block/nvme2n1/device/model
Samsung SSD 970 PRO 512GB
# cat /sys/fs/cgroup/io.cost.model
259:0 ctrl=user model=linear rbps=834913556 rseqiops=93622 rrandiops=102913 wbps=618985353 wseqiops=72325 wrandiops=71025
# cat /sys/fs/cgroup/io.cost.qos
259:0 enable=1 ctrl=user rpct=95.00 rlat=18776 wpct=95.00 wlat=8897 min=60.00 max=100.00
# resctl-bench -m 29.6G -r out.json run protection::scenario=mem-hog,loops=1
...
Memory Hog Summary
==================
IO Latency: R p50=242u:336u/2.5m p90=794u:1.4m/7.5m p99=2.7m:8.0m/62.5m max=8.0m:36.4m/350m
W p50=221u:323u/1.5m p90=709u:1.2m/5.5m p99=1.5m:2.5m/9.5m max=6.9m:35.9m/350m
Isolation and Request Latency Impact Distributions:
min p01 p05 p10 p25 p50 p75 p90 p95 p99 max mean stdev
isol% 15.90 15.90 15.90 40.05 57.24 59.07 60.01 74.63 74.63 90.35 90.35 58.12 15.82
lat-imp% 0 0 0 0 0 4.55 14.68 15.54 233.5 548.1 548.1 53.88 143.6
Result: isol=58.12:15.82% lat_imp=53.88%:143.6 work_csv=100.0% missing=3.96%
The isolation result of 58.12% is close to what this device would show
without any IO control.
Fix it by introducing a new flag BIO_QOS_MERGED to mark merged bios and
calling rq_qos_done_bio() on them too. For consistency and clarity, rename
BIO_TRACKED to BIO_QOS_THROTTLED. The flag checks are moved into
rq_qos_done_bio() so that it's next to the code paths that set the flags.
With the patch applied, the above same benchmark shows:
# resctl-bench -m 29.6G -r out.json run protection::scenario=mem-hog,loops=1
...
Memory Hog Summary
==================
IO Latency: R p50=123u:84.4u/985u p90=322u:256u/2.5m p99=1.6m:1.4m/9.5m max=11.1m:36.0m/350m
W p50=429u:274u/995u p90=1.7m:1.3m/4.5m p99=3.4m:2.7m/11.5m max=7.9m:5.9m/26.5m
Isolation and Request Latency Impact Distributions:
min p01 p05 p10 p25 p50 p75 p90 p95 p99 max mean stdev
isol% 84.91 84.91 89.51 90.73 92.31 94.49 96.36 98.04 98.71 100.0 100.0 94.42 2.81
lat-imp% 0 0 0 0 0 2.81 5.73 11.11 13.92 17.53 22.61 4.10 4.68
Result: isol=94.42:2.81% lat_imp=4.10%:4.68 work_csv=58.34% missing=0%
References
Impacted products
| Vendor | Product | Version | |||||||
|---|---|---|---|---|---|---|---|---|---|
| ▼ | Linux | Linux |
Version: a647a524a46736786c95cdb553a070322ca096e3 Version: a647a524a46736786c95cdb553a070322ca096e3 Version: a647a524a46736786c95cdb553a070322ca096e3 Version: a647a524a46736786c95cdb553a070322ca096e3 Version: db60edbfff332a6a5477c367af8125f034570989 Version: 004b8f8a691205a93d9e80d98b786b2b97424d6e |
||||||
|
|||||||||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"block/bio.c",
"block/blk-iolatency.c",
"block/blk-rq-qos.h",
"include/linux/blk_types.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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},
{
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"version": "a647a524a46736786c95cdb553a070322ca096e3",
"versionType": "git"
},
{
"lessThan": "09737db4c891eba25e6f6383a7c38afd4acc883f",
"status": "affected",
"version": "a647a524a46736786c95cdb553a070322ca096e3",
"versionType": "git"
},
{
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{
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{
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"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"block/bio.c",
"block/blk-iolatency.c",
"block/blk-rq-qos.h",
"include/linux/blk_types.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.15"
},
{
"lessThan": "5.15",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.54",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.16.*",
"status": "unaffected",
"version": "5.16.19",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.17.*",
"status": "unaffected",
"version": "5.17.2",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "5.18",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.54",
"versionStartIncluding": "5.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.16.19",
"versionStartIncluding": "5.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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},
{
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},
{
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],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblock: fix rq-qos breakage from skipping rq_qos_done_bio()\n\na647a524a467 (\"block: don\u0027t call rq_qos_ops-\u003edone_bio if the bio isn\u0027t\ntracked\") made bio_endio() skip rq_qos_done_bio() if BIO_TRACKED is not set.\nWhile this fixed a potential oops, it also broke blk-iocost by skipping the\ndone_bio callback for merged bios.\n\nBefore, whether a bio goes through rq_qos_throttle() or rq_qos_merge(),\nrq_qos_done_bio() would be called on the bio on completion with BIO_TRACKED\ndistinguishing the former from the latter. rq_qos_done_bio() is not called\nfor bios which wenth through rq_qos_merge(). This royally confuses\nblk-iocost as the merged bios never finish and are considered perpetually\nin-flight.\n\nOne reliably reproducible failure mode is an intermediate cgroup geting\nstuck active preventing its children from being activated due to the\nleaf-only rule, leading to loss of control. The following is from\nresctl-bench protection scenario which emulates isolating a web server like\nworkload from a memory bomb run on an iocost configuration which should\nyield a reasonable level of protection.\n\n # cat /sys/block/nvme2n1/device/model\n Samsung SSD 970 PRO 512GB\n # cat /sys/fs/cgroup/io.cost.model\n 259:0 ctrl=user model=linear rbps=834913556 rseqiops=93622 rrandiops=102913 wbps=618985353 wseqiops=72325 wrandiops=71025\n # cat /sys/fs/cgroup/io.cost.qos\n 259:0 enable=1 ctrl=user rpct=95.00 rlat=18776 wpct=95.00 wlat=8897 min=60.00 max=100.00\n # resctl-bench -m 29.6G -r out.json run protection::scenario=mem-hog,loops=1\n ...\n Memory Hog Summary\n ==================\n\n IO Latency: R p50=242u:336u/2.5m p90=794u:1.4m/7.5m p99=2.7m:8.0m/62.5m max=8.0m:36.4m/350m\n W p50=221u:323u/1.5m p90=709u:1.2m/5.5m p99=1.5m:2.5m/9.5m max=6.9m:35.9m/350m\n\n Isolation and Request Latency Impact Distributions:\n\n min p01 p05 p10 p25 p50 p75 p90 p95 p99 max mean stdev\n isol% 15.90 15.90 15.90 40.05 57.24 59.07 60.01 74.63 74.63 90.35 90.35 58.12 15.82\n lat-imp% 0 0 0 0 0 4.55 14.68 15.54 233.5 548.1 548.1 53.88 143.6\n\n Result: isol=58.12:15.82% lat_imp=53.88%:143.6 work_csv=100.0% missing=3.96%\n\nThe isolation result of 58.12% is close to what this device would show\nwithout any IO control.\n\nFix it by introducing a new flag BIO_QOS_MERGED to mark merged bios and\ncalling rq_qos_done_bio() on them too. For consistency and clarity, rename\nBIO_TRACKED to BIO_QOS_THROTTLED. The flag checks are moved into\nrq_qos_done_bio() so that it\u0027s next to the code paths that set the flags.\n\nWith the patch applied, the above same benchmark shows:\n\n # resctl-bench -m 29.6G -r out.json run protection::scenario=mem-hog,loops=1\n ...\n Memory Hog Summary\n ==================\n\n IO Latency: R p50=123u:84.4u/985u p90=322u:256u/2.5m p99=1.6m:1.4m/9.5m max=11.1m:36.0m/350m\n W p50=429u:274u/995u p90=1.7m:1.3m/4.5m p99=3.4m:2.7m/11.5m max=7.9m:5.9m/26.5m\n\n Isolation and Request Latency Impact Distributions:\n\n min p01 p05 p10 p25 p50 p75 p90 p95 p99 max mean stdev\n isol% 84.91 84.91 89.51 90.73 92.31 94.49 96.36 98.04 98.71 100.0 100.0 94.42 2.81\n lat-imp% 0 0 0 0 0 2.81 5.73 11.11 13.92 17.53 22.61 4.10 4.68\n\n Result: isol=94.42:2.81% lat_imp=4.10%:4.68 work_csv=58.34% missing=0%"
}
],
"providerMetadata": {
"dateUpdated": "2025-08-28T14:42:36.939Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/af9452dfdba4bf7359ef7645eee2d243a1df0649"
},
{
"url": "https://git.kernel.org/stable/c/dbd20bb904ad5731aaca8d009367a930d6ada111"
},
{
"url": "https://git.kernel.org/stable/c/09737db4c891eba25e6f6383a7c38afd4acc883f"
},
{
"url": "https://git.kernel.org/stable/c/aa1b46dcdc7baaf5fec0be25782ef24b26aa209e"
}
],
"title": "block: fix rq-qos breakage from skipping rq_qos_done_bio()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2022-49266",
"datePublished": "2025-02-26T01:56:15.709Z",
"dateReserved": "2025-02-26T01:49:39.297Z",
"dateUpdated": "2025-08-28T14:42:36.939Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.1"
}