In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
serial: msm: Disable DMA for kernel console UART<\/p>\n
At the moment, concurrent writes from userspace and the kernel to the
\nconsole can trigger a race condition that results in an infinite loop of
\nthe same messages printed over and over again. This is most likely to
\nhappen during system startup or shutdown when the init system starts\/stops
\na large number of system services that interact with various kernel code.<\/p>\n
When userspace writes to the TTY device, the driver initiates an
\nasynchronous DMA transfer and releases the port lock. At the same moment,
\nthe kernel printk path might grab the port lock and re-configure the UART
\ncontroller for PIO, without waiting for the DMA operation to complete. It
\nseems like this collision results in zero progress being reported for the
\nDMA engine, so the same text is printed to the console over and over again.<\/p>\n
For the kernel console, we want a reliable output path that will be
\nfunctional even during crashes etc. So rather than implementing complex
\ncode to synchronize the kernel console write routines with the userspace
\nDMA write routines, simply disable DMA for the console UART instance.<\/p>\n
Similar checks exist in many other serial drivers, e.g. 8250_port.c,
\nimx.c, sh-sci.c etc.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
serial: msm: Disable DMA for kernel console UART<\/p>\n
At the moment, concurrent writes from userspace and the kernel to the
\nconsole can<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-17434","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/17434","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=17434"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=17434"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=17434"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}