{"id":"CVE-2026-90193","state":"PUBLISHED","title":"mailbox: qcom-cpucp: fix PREEMPT_RT self-deadlock in IRQ handler","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.","publishedAt":"2026-09-17T16:07:13.672Z","updatedAt":"2026-10-19T08:59:29.783Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"0e2a9a03106cd5fa0dbc9047675e7645c55e2669","status":"affected","lessThan":"aa482273f32117c3adeba9b1cc945e0b5d33722d","versionType":"git"},{"version":"0e2a9a03106cd5fa0dbc9047675e7645c55e2669","status":"affected","lessThan":"8b8de6400c86937ed57d680d06d716e167b381de","versionType":"git"},{"version":"0e2a9a03106cd5fa0dbc9047675e7645c55e2669","status":"affected","lessThan":"e40b3edeaf25cd09e9c88edb1ef99373ca37593b","versionType":"git"},{"version":"0e2a9a03106cd5fa0dbc9047675e7645c55e2669","status":"affected","lessThan":"3690aaa6d18f6775c3e7932fb8af8c5bf6a6b69c","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/mailbox/qcom-cpucp-mbox.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.11","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/mailbox/qcom-cpucp-mbox.c"]}],"references":["https://git.kernel.org/stable/c/aa482273f32117c3adeba9b1cc945e0b5d33722d","https://git.kernel.org/stable/c/8b8de6400c86937ed57d680d06d716e167b381de","https://git.kernel.org/stable/c/e40b3edeaf25cd09e9c88edb1ef99373ca37593b","https://git.kernel.org/stable/c/3690aaa6d18f6775c3e7932fb8af8c5bf6a6b69c"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:34.582Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/90xxx/CVE-2026-90193.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-90193","state":"PUBLISHED","datePublished":"2026-09-17T16:07:13.672Z","dateUpdated":"2026-10-19T08:59:29.783Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.792Z"},"containers":{"cna":{"title":"mailbox: qcom-cpucp: fix PREEMPT_RT self-deadlock in IRQ handler","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"0e2a9a03106cd5fa0dbc9047675e7645c55e2669","status":"affected","lessThan":"aa482273f32117c3adeba9b1cc945e0b5d33722d","versionType":"git"},{"version":"0e2a9a03106cd5fa0dbc9047675e7645c55e2669","status":"affected","lessThan":"8b8de6400c86937ed57d680d06d716e167b381de","versionType":"git"},{"version":"0e2a9a03106cd5fa0dbc9047675e7645c55e2669","status":"affected","lessThan":"e40b3edeaf25cd09e9c88edb1ef99373ca37593b","versionType":"git"},{"version":"0e2a9a03106cd5fa0dbc9047675e7645c55e2669","status":"affected","lessThan":"3690aaa6d18f6775c3e7932fb8af8c5bf6a6b69c","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/mailbox/qcom-cpucp-mbox.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.11","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/mailbox/qcom-cpucp-mbox.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/aa482273f32117c3adeba9b1cc945e0b5d33722d"},{"url":"https://git.kernel.org/stable/c/8b8de6400c86937ed57d680d06d716e167b381de"},{"url":"https://git.kernel.org/stable/c/e40b3edeaf25cd09e9c88edb1ef99373ca37593b"},{"url":"https://git.kernel.org/stable/c/3690aaa6d18f6775c3e7932fb8af8c5bf6a6b69c"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:59:29.783Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.12.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.18.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"7.2.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}