In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
perf\/x86\/intel: Prevent drain_pebs() reentry<\/p>\n
The PEBS buffer is shared by all events on a CPU, so drain_pebs() must
\nnot be reentered. If so, one instance may observe stale buffer state and
\npotentially access out-of-bound memory.<\/p>\n
Most invocations happen in NMI context, which naturally prevents reentry.
\nHowever, drain_pebs() is also reachable from process context via
\nintel_pmu_drain_pebs_buffer().<\/p>\n
In those paths, the PMU is often already disabled, but not guaranteed.
\nFor example, __intel_pmu_pebs_disable() only disables the target counter,
\nso other active counters can still raise a PMI and interrupt an in-flight
\ndrain_pebs(). Here is an example,<\/p>\n
__perf_addr_filters_adjust()
\n perf_event_stop()
\n __perf_event_stop()
\n x86_pmu_stop() (event->pmu->stop)
\n intel_pmu_disable_event()
\n intel_pmu_pebs_disable()
\n __intel_pmu_pebs_disable()
\n intel_pmu_drain_large_pebs()
\n intel_pmu_drain_pebs_buffer()<\/p>\n
Introduce __intel_pmu_quiesce() and __intel_pmu_resume() helpers and
\nuse them in intel_pmu_drain_large_pebs() to disable the full PMU
\naround the intel_pmu_drain_pebs_buffer() call, preventing reentry.<\/p>\n
Also add a warning in intel_pmu_drain_pebs_buffer() when the full PMU is
\nnot disabled.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
perf\/x86\/intel: Prevent drain_pebs() reentry<\/p>\n
The PEBS buffer is shared by all events on a CPU, so drain_pebs() must
\nnot be reenter<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-29116","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/29116","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=29116"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=29116"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=29116"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}