CVE-2026-90100 (GCVE-0-2026-90100)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:06 – Updated: 2026-10-19 08:57
VLAI
Title
ptp: netc: fix period truncation and potential divide-by-zero in PEROUT
Summary
In the Linux kernel, the following vulnerability has been resolved: ptp: netc: fix period truncation and potential divide-by-zero in PEROUT The max_period bound in net_timer_enable_perout() was computed as: max_period = (u64)NETC_TMR_DEFAULT_FIPER + integral_period; which exceeds U32_MAX when integral_period > 0 (e.g. 0x100000002 for the default 333333333 Hz clock). A period_ns that passes this check but exceeds U32_MAX is then silently truncated when stored into the u32 struct netc_pp::period field. A truncated value of zero can reach netc_timer_set_perout_alarm(), where the local u32 period variable would also be 0, causing a divide-by-zero in roundup_u64(delta, period) whenever the stime < min_time branch is taken (which always happens for a start time of {0, 0}). Additionally, netc_timer_enable_periodic_pulse() and netc_timer_enable_fiper() both compute: fiper = pp->period - integral_period; A zero pp->period results in an unsigned wraparound to 0xFFFFFFFD, mis-programming the FIPER hardware register. Fix all three issues by capping max_period at NETC_TMR_DEFAULT_FIPER (0xFFFFFFFF). This ensures that any period_ns passing the range check fits in a u32 without truncation, so the stored value is always valid and non-zero. The accepted range is reduced by integral_period ns (typically only a few nanoseconds), which is negligible in practice.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6971 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 671e266835b8a87d6cc2c6db962de23783405dd8 , < 51fe3fe0ffec033bd831c71d9bee3dee827e491c (git)
Affected: 671e266835b8a87d6cc2c6db962de23783405dd8 , < 08988d1941e180f0ad30d91233cb64f3418ba23c (git)
Affected: 671e266835b8a87d6cc2c6db962de23783405dd8 , < 777dbc9914b2f003f1d44af80c7a4a395c5961b2 (git)
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Linux Linux Affected: 6.18
Unaffected: 0 , < 6.18 (semver)
Unaffected: 6.18.52 , ≤ 6.18.* (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "drivers/ptp/ptp_netc.c"
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              "status": "affected",
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nptp: netc: fix period truncation and potential divide-by-zero in PEROUT\n\nThe max_period bound in net_timer_enable_perout() was computed as:\n\n  max_period = (u64)NETC_TMR_DEFAULT_FIPER + integral_period;\n\nwhich exceeds U32_MAX when integral_period \u003e 0 (e.g. 0x100000002 for\nthe default 333333333 Hz clock). A period_ns that passes this check but\nexceeds U32_MAX is then silently truncated when stored into the u32\nstruct netc_pp::period field.\n\nA truncated value of zero can reach netc_timer_set_perout_alarm(), where\nthe local u32 period variable would also be 0, causing a divide-by-zero\nin roundup_u64(delta, period) whenever the stime \u003c min_time branch is\ntaken (which always happens for a start time of {0, 0}).\n\nAdditionally, netc_timer_enable_periodic_pulse() and\nnetc_timer_enable_fiper() both compute:\n\n  fiper = pp-\u003eperiod - integral_period;\n\nA zero pp-\u003eperiod results in an unsigned wraparound to 0xFFFFFFFD,\nmis-programming the FIPER hardware register.\n\nFix all three issues by capping max_period at NETC_TMR_DEFAULT_FIPER\n(0xFFFFFFFF). This ensures that any period_ns passing the range check\nfits in a u32 without truncation, so the stored value is always valid\nand non-zero. The accepted range is reduced by integral_period ns\n(typically only a few nanoseconds), which is negligible in practice."
        }
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      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:57:58.302Z",
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        "shortName": "Linux"
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    "cveId": "CVE-2026-90100",
    "datePublished": "2026-09-17T16:06:11.515Z",
    "dateReserved": "2026-09-11T19:38:34.786Z",
    "dateUpdated": "2026-10-19T08:57:58.302Z",
    "state": "PUBLISHED"
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      "title": "ptp: netc: fix period truncation and potential divide-by-zero in PEROUT",
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        "descriptions": [
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            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nptp: netc: fix period truncation and potential divide-by-zero in PEROUT\n\nThe max_period bound in net_timer_enable_perout() was computed as:\n\n  max_period = (u64)NETC_TMR_DEFAULT_FIPER + integral_period;\n\nwhich exceeds U32_MAX when integral_period \u003e 0 (e.g. 0x100000002 for\nthe default 333333333 Hz clock). A period_ns that passes this check but\nexceeds U32_MAX is then silently truncated when stored into the u32\nstruct netc_pp::period field.\n\nA truncated value of zero can reach netc_timer_set_perout_alarm(), where\nthe local u32 period variable would also be 0, causing a divide-by-zero\nin roundup_u64(delta, period) whenever the stime \u003c min_time branch is\ntaken (which always happens for a start time of {0, 0}).\n\nAdditionally, netc_timer_enable_periodic_pulse() and\nnetc_timer_enable_fiper() both compute:\n\n  fiper = pp-\u003eperiod - integral_period;\n\nA zero pp-\u003eperiod results in an unsigned wraparound to 0xFFFFFFFD,\nmis-programming the FIPER hardware register.\n\nFix all three issues by capping max_period at NETC_TMR_DEFAULT_FIPER\n(0xFFFFFFFF). This ensures that any period_ns passing the range check\nfits in a u32 without truncation, so the stored value is always valid\nand non-zero. The accepted range is reduced by integral_period ns\n(typically only a few nanoseconds), which is negligible in practice."
          }
        ],
        "id": "CVE-2026-90100",
        "lastModified": "2026-10-19T09:18:59.243",
        "metrics": {},
        "published": "2026-09-17T17:17:01.680",
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      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2026/cve-2026-90100.json",
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}



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