{"id":"CVE-2026-90100","title":"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_TM…","summary":"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_TM…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 671e266835b8a87d6cc2c6db962de23783405dd8 < 51fe3fe0ffec033bd831c71d9bee3dee827e491c","Linux >= 671e266835b8a87d6cc2c6db962de23783405dd8 < 08988d1941e180f0ad30d91233cb64f3418ba23c","Linux >= 671e266835b8a87d6cc2c6db962de23783405dd8 < 777dbc9914b2f003f1d44af80c7a4a395c5961b2","Linux 6.18"],"published":"2026-09-17","updated":"2026-09-17","sourceUpdated":"2026-09-17T17:17:01.680","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-90100","references":[{"url":"https://git.kernel.org/stable/c/08988d1941e180f0ad30d91233cb64f3418ba23c","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/51fe3fe0ffec033bd831c71d9bee3dee827e491c","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/777dbc9914b2f003f1d44af80c7a4a395c5961b2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-09-17T16:21:47.890Z","epss":0.00198,"epssPercentile":0.09822,"slug":"CVE-2026-90100","body":"## Overview\n\nIn 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 > 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 < 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->period - integral_period;\n\nA zero pp->period 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}