ptp: netc: fix period truncation and potential divide-by-zero in PEROUT

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-90100
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-17 17:17:01 UTC
Updated2026-09-17 17:17:01 UTC
DescriptionIn 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.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 671e266835b8a87d6cc2c6db962de23783405dd8 51fe3fe0ffec033bd831c71d9bee3dee827e491c git Not specified
CNA Linux Linux affected 671e266835b8a87d6cc2c6db962de23783405dd8 08988d1941e180f0ad30d91233cb64f3418ba23c git Not specified
CNA Linux Linux affected 671e266835b8a87d6cc2c6db962de23783405dd8 777dbc9914b2f003f1d44af80c7a4a395c5961b2 git Not specified
CNA Linux Linux affected 6.18 Not specified
CNA Linux Linux unaffected 6.18 semver Not specified
CNA Linux Linux unaffected 6.18.52 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.6 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/777dbc9914b2f003f1d44af80c7a4a395c5961b2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/08988d1941e180f0ad30d91233cb64f3418ba23c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/51fe3fe0ffec033bd831c71d9bee3dee827e491c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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