{"id":"CVE-2026-90193","summary":"mailbox: qcom-cpucp: fix PREEMPT_RT self-deadlock in IRQ handler","details":"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-\u003elock. 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() -\u003e mbox_send_message() -\u003e add_to_rbuf(),\nwhich attempts to re-acquire the same chan-\u003elock. 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 -\u003e mbox_send_message -\u003e mailbox_clear_channel -\u003e\n  scmi_rx_callback -\u003e mbox_chan_received_data [\u003c- held chan-\u003elock here]\n\nFix by saving chan-\u003ecl 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-\u003ecl access while\navoiding the lock re-entrancy that causes the PREEMPT_RT deadlock.","modified":"2026-09-18T03:48:36.076567554Z","published":"2026-09-17T16:07:13.672Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90193.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3690aaa6d18f6775c3e7932fb8af8c5bf6a6b69c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8b8de6400c86937ed57d680d06d716e167b381de"},{"type":"WEB","url":"https://git.kernel.org/stable/c/aa482273f32117c3adeba9b1cc945e0b5d33722d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e40b3edeaf25cd09e9c88edb1ef99373ca37593b"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90193.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90193"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0e2a9a03106cd5fa0dbc9047675e7645c55e2669"},{"fixed":"aa482273f32117c3adeba9b1cc945e0b5d33722d"},{"fixed":"8b8de6400c86937ed57d680d06d716e167b381de"},{"fixed":"e40b3edeaf25cd09e9c88edb1ef99373ca37593b"},{"fixed":"3690aaa6d18f6775c3e7932fb8af8c5bf6a6b69c"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90193.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.11.0"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.52"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90193.json"}}],"schema_version":"1.9.0"}