In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
mm\/kmemleak: avoid soft lockup when scanning task stacks<\/p>\n
Patch series “mm\/kmemleak: avoid soft lockup when scanning task”, v3.<\/p>\n
kmemleak_scan() scans every task stack under one rcu_read_lock() with no
\nreschedule point, which can trip the soft lockup watchdog on hosts with
\nvery many threads.<\/p>\n
That prints the following message, depending on the workload+host
\nconfiguration:<\/p>\n
watchdog: BUG: soft lockup – CPU#35 stuck for 22s! [kmemleak:537]
\n scan_block
\n kmemleak_scan
\n kmemleak_scan_thread
\n kthread<\/p>\n
Patch 1 walks the tasks with find_ge_pid() so the scan reschedules between
\ntasks<\/p>\n
Patches 2-3 let the scan loops stop early once a scan is interrupted.<\/p>\n
This patch (of 3):<\/p>\n
kmemleak_scan() walks every thread and scans its kernel stack under a
\nsingle rcu_read_lock() with no reschedule point. On a host with very many
\nthreads — amplified by KASAN\/lockdep in debug builds — this loop can hog
\na CPU long enough to trip the soft lockup watchdog:<\/p>\n
watchdog: BUG: soft lockup – CPU#35 stuck for 22s! [kmemleak:537]
\n scan_block
\n kmemleak_scan
\n kmemleak_scan_thread
\n kthread<\/p>\n
A cond_resched() cannot be added directly: the loop runs inside an RCU
\nread-side critical section.<\/p>\n
Walk the tasks one PID at a time with find_ge_pid(), taking the RCU read
\nlock only to look up and pin each task. The stack is then scanned with no
\nlock held, so cond_resched() runs between tasks and the scan stops early
\non scan_should_stop(). This follows the next_tgid()\/task_seq_get_next()
\niteration pattern and keeps each RCU critical section short.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
mm\/kmemleak: avoid soft lockup when scanning task stacks<\/p>\n
Patch series “mm\/kmemleak: avoid soft lockup when scanning task”, v3.<\/p>\n
km<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-21681","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/21681","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=21681"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=21681"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=21681"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}