In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
mailbox: qcom-cpucp: fix PREEMPT_RT self-deadlock in IRQ handler<\/p>\n
qcom_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.<\/p>\n
The 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.<\/p>\n
This 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 [lock here]<\/p>\n
Fix 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.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
mailbox: qcom-cpucp: fix PREEMPT_RT self-deadlock in IRQ handler<\/p>\n
qcom_cpucp_mbox_irq_fn() calls mbox_chan_received_data() while ho<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-25602","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/25602","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=25602"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=25602"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=25602"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}