In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
fprobe: Use guard(rcu_sched_notrace) and check rcu_is_watching()<\/p>\n
unregister_fprobe() and unregister_fprobe_async() (used by BPF
\nkprobe-multi) rely on standard RCU grace periods (synchronize_rcu()
\nand call_rcu()) to wait until in-flight fprobe handlers complete before
\nfreeing the fprobe.<\/p>\n
However, if an fprobe handler executes while RCU is not watching (such
\nas in the idle loop or nohz_full extended quiescent states), standard
\nRCU does not track preemption-disabled sections. Consequently,
\nsynchronize_rcu() does not wait for those executions, which can lead
\nto a use-after-free if the fprobe is freed immediately after
\nunregistration. Ensure handlers exit early when !rcu_is_watching().<\/p>\n
Furthermore, fprobe_fgraph_entry() and fprobe_ftrace_entry() previously
\nused guard(rcu)() and rcu_read_lock(), which invoke lockdep on every
\nhit under CONFIG_PROVE_LOCKING. This adds overhead and can cause lockdep
\nrecursion if probed functions interact with lockdep.<\/p>\n
Since rhltable_lookup() and rhl_for_each_entry_rcu() use
\nrcu_dereference_all_check() (which checks rcu_read_lock_any_held()),
\nholding preemption disabled via rcu_read_lock_sched_notrace() is fully
\nvalid and sufficient so long as rcu_is_watching() is true.<\/p>\n
Define and use guard(rcu_sched_notrace)() across fprobe_ftrace_entry(),
\nfprobe_fgraph_entry(), and fprobe_return(). This eliminates fast-path
\nrcu_read_lock() and lockdep overhead while guaranteeing safe grace
\nperiod synchronization.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
fprobe: Use guard(rcu_sched_notrace) and check rcu_is_watching()<\/p>\n
unregister_fprobe() and unregister_fprobe_async() (used by BPF
\nkp<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-41333","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/41333","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=41333"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=41333"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=41333"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}