In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
net\/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF<\/p>\n
The teql master->slaves singly linked list is not protected against
\nmultiple writes. It can be mod’ed concurently from teql_master_xmit(),
\nteql_dequeue(), teql_init() and teql_destroy() without holding any list
\nlock or RCU protection.<\/p>\n
zdi-disclosures@trendmicro.com has demonstrated that the qdisc is freed
\nafter an RCU grace period, but teql_master_xmit() running on another
\nCPU can still hold a stale pointer into the list, resulting in a
\nslab-use-after-free:<\/p>\n
BUG: KASAN: slab-use-after-free in teql_master_xmit+0xf0f\/0x16b0
\nRead of size 8 at addr ffff888013fb0440 by task poc\/332
\nFreed 512-byte region [ffff888013fb0400, ffff888013fb0600) (kmalloc-512)<\/p>\n
The fix?
\nAdd a per-master slaves_lock spinlock that serializes all mutations of
\nmaster->slaves and the NEXT_SLAVE() links in teql_destroy() and
\nteql_qdisc_init(). teql_master_xmit() also takes the same slaves_lock
\naround those updates.
\nAnnotate master->slaves and the per-slave ->next pointer with __rcu and
\nuse the appropriate RCU accessors everywhere they are touched:
\nrcu_assign_pointer() on the writer side (under slaves_lock),
\nrcu_dereference_protected() for the writer-side loads (also under
\nslaves_lock), rcu_dereference_bh() for the loads in teql_master_xmit() and
\nrtnl_dereference() for the loads in teql_master_open()\/teql_master_mtu(),
\nwhich run under RTNL.
\nPair this with rcu_read_lock_bh()\/rcu_read_unlock_bh() around the list
\ntraversal in teql_master_xmit(), so that readers either observe a fully
\nlinked list or are deferred until the in-flight mutation completes. The two
\nearly-return paths in teql_master_xmit() are updated to release the RCU-bh
\nread-side critical section before returning, since leaving it held would
\ndisable BH on that CPU for good.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
net\/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF<\/p>\n
The teql master->slaves singly linked list is not prote<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-7033","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/7033","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=7033"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=7033"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=7033"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}