sched: sch_cake: add bounds checks to host bulk flow fairness counts
In the Linux kernel, the following vulnerability has been resolved: sched: sch_cake: add bounds checks to host bulk flow fairness counts Even though we fixed a logic error in the commit cited below, syzbot still managed to trigger an underflow of the per-host bulk flow counters, leading to an out of bounds memory access. To avoid any such logic errors causing out of bounds memory accesses, this commit factors out all accesses to the per-host bulk flow counters to a series of helpers that perform bounds-checking before any increments and decrements. This also has the benefit of improving readability by moving the conditional checks for the flow mode into these helpers, instead of having them spread out throughout the code (which was the cause of the original logic error). As part of this change, the flow quantum calculation is consolidated into a helper function, which means that the dithering applied to the ost load scaling is now applied both in the DRR rotation and when a sparse flow's quantum is first initiated. The only user-visible effect of this is that the maximum packet size that can be sent while a flow stays sparse will now vary with +/- one byte in some cases. This should not make a noticeable difference in practice, and thus it's not worth complicating the code to preserve the old behaviour.
CVE-2025-21647
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2025-21647
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4a4eeefa514db570be025ab46d779af180e2c9bb",
"lessThan": "44fe1efb4961c1a5ccab16bb579dfc6b308ad58b",
"versionType": "git"
},
{
"status": "affected",
"version": "7725152b54d295b7da5e34c2f419539b30d017bd",
"lessThan": "b1a1743aaa4906c41c426eda97e2e2586f79246d",
"versionType": "git"
},
{
"status": "affected",
"version": "cde71a5677971f4f1b69b25e854891dbe78066a4",
"lessThan": "bb0245fa72b783cb23a9949c5048781341e91423",
"versionType": "git"
},
{
"status": "affected",
"version": "549e407569e08459d16122341d332cb508024094",
"lessThan": "a777e06dfc72bed73c05dcb437d7c27ad5f90f3f",
"versionType": "git"
},
{
"status": "affected",
"version": "d4a9039a7b3d8005b90c7b1a55a306444f0e5447",
"lessThan": "27202e2e8721c3b23831563c36ed5ac7818641ba",
"versionType": "git"
},
{
"status": "affected",
"version": "546ea84d07e3e324644025e2aae2d12ea4c5896e",
"lessThan": "91bb18950b88f955838ec0c1d97f74d135756dc7",
"versionType": "git"
},
{
"status": "affected",
"version": "546ea84d07e3e324644025e2aae2d12ea4c5896e",
"lessThan": "737d4d91d35b5f7fa5bb442651472277318b0bfd",
"versionType": "git"
},
{
"status": "affected",
"version": "d7c01c0714c04431b5e18cf17a9ea68a553d1c3c",
"versionType": "git"
},
{
"status": "affected",
"version": "5.4.284",
"lessThan": "5.4.291",
"versionType": "semver"
},
{
"status": "affected",
"version": "5.10.226",
"lessThan": "5.10.235",
"versionType": "semver"
},
{
"status": "affected",
"version": "5.15.167",
"lessThan": "5.15.179",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.1.110",
"lessThan": "6.1.125",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.6.51",
"lessThan": "6.6.72",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.10.10",
"lessThan": "6.11",
"versionType": "semver"
}
],
"programFiles": [
"net/sched/sch_cake.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.11"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.11",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.4.291",
"versionType": "semver",
"lessThanOrEqual": "5.4.*"
},
{
"status": "unaffected",
"version": "5.10.235",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.179",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.125",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.72",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.10",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.13",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/sched/sch_cake.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2025-21647
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #26897 · Revision 1
- Added to Heist Feed
- Publisher date