{"cve":"CVE-2026-90193","nvd":{"published":"2026-09-17T17:17:14.030","modified":"2026-10-19T09:19:09.310","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmailbox: qcom-cpucp: fix PREEMPT_RT self-deadlock in IRQ handler\n\nqcom_cpucp_mbox_irq_fn() calls mbox_chan_received_data() while holding\nchan->lock. Under PREEMPT_RT, spin_lock_irqsave() is converted to an\nrt_spinlock (rtmutex-based), which tracks ownership and can sleep.\n\nThe callback chain triggered by mbox_chan_received_data() eventually\nreaches mailbox_clear_channel() -> mbox_send_message() -> add_to_rbuf(),\nwhich attempts to re-acquire the same chan->lock. Since rtmutex detects\nthe re-entrant lock attempt by the same owner, the thread blocks waiting\nfor a lock it already holds, causing a permanent deadlock.\n\nThis deadlock manifests as 'irq/N-apss_cpucp_mbox' stuck in D state\nwith the following call trace:\n  rt_spin_lock -> mbox_send_message -> mailbox_clear_channel ->\n  scmi_rx_callback -> mbox_chan_received_data [<- held chan->lock here]\n\nFix by saving chan->cl locally and clearing the HW interrupt register\ninside the lock, then invoking mbox_chan_received_data() after releasing\nthe lock. This preserves the mutual exclusion for chan->cl access while\navoiding the lock re-entrancy that causes the PREEMPT_RT deadlock.","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/3690aaa6d18f6775c3e7932fb8af8c5bf6a6b69c","https://git.kernel.org/stable/c/8b8de6400c86937ed57d680d06d716e167b381de","https://git.kernel.org/stable/c/aa482273f32117c3adeba9b1cc945e0b5d33722d","https://git.kernel.org/stable/c/e40b3edeaf25cd09e9c88edb1ef99373ca37593b"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:55:23.253742848+00:00"},"epss":{"cve":"CVE-2026-90193","score":0.00209,"percentile":0.1093,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}