In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
dmaengine: wait for RCU readers before releasing dma_device<\/p>\n
dma_issue_pending_all() walks the dma_device_list with
\nlist_for_each_entry_rcu() under rcu_read_lock(). dma_device_release()
\nunlinks the device with list_del_rcu() and then calls
\ndevice->device_release() (which in many drivers, such as plx_dma.c,
\ndirectly calls kfree()).<\/p>\n
Because there is no grace period between unlinking the device and
\nfreeing it, concurrent RCU readers in dma_issue_pending_all() can
\naccess the device after it has been freed.<\/p>\n
The lockless walk originally relied on clients holding a dmaengine
\nreference to pin the provider module, and therefore the device, for as
\nlong as they might traverse the list. Commit 8ad342a86359 (“dmaengine:
\nAdd reference counting to dma_device struct”) decoupled the dma_device
\nlifetime from the module reference, so the device can now be released
\nwhile a reader is still walking the list.<\/p>\n
Add synchronize_rcu() before the device is freed, so RCU readers are
\nguaranteed to have finished. Keep it unconditional: providers that do
\nnot implement device_release() free the device themselves once
\ndma_async_device_unregister() returns. This call will delay for a grace
\nperiod with dma_list_mutex held, which is safe and only teardown path is
\ndelayed.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
dmaengine: wait for RCU readers before releasing dma_device<\/p>\n
dma_issue_pending_all() walks the dma_device_list with
\nlist_for_each_e<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-33411","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/33411","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=33411"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=33411"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=33411"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}