In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
ALSA: seq: close a re-opened queue timer in the destructor<\/p>\n
queue_delete() closes the queue timer, then frees it. snd_seq_timer_close()
\nclears q->timer->timeri. snd_use_lock_sync() then drains borrowers, and
\nsnd_seq_timer_delete() frees q->timer.<\/p>\n
A borrower can re-open the timer inside that window. A SET_QUEUE_CLIENT
\nthat took a queueptr() use_lock reference before the queue was unlinked
\nruns snd_seq_timer_open() after the close. Open refuses re-open only while
\ntimeri is set, and the close just cleared it, so it re-opens timeri.<\/p>\n
snd_seq_timer_delete() does not close that instance. Its snd_seq_timer_stop()
\nis a no-op, because running was cleared first. So it frees q->timer with the
\ninstance still live. The queue is freed next.<\/p>\n
The instance stays on the global timer with callback_data pointing at the
\nfreed queue. A non-owner START on the unlocked queue arms it. The next tick
\nderefs the freed queue in snd_seq_timer_interrupt().<\/p>\n
Reachable by an unprivileged user with access to \/dev\/snd\/seq. No CAP and
\nno queue ownership required.<\/p>\n
Close any lingering instance in the destructor. There, ->timeri can no
\nlonger change: the queue is unlinked and all use_lock borrowers have
\ndrained, so no snd_seq_queue_use() can re-open it. Close it before clearing
\nq->timer. snd_timer_close() waits for any in-flight snd_seq_timer_interrupt()
\nto finish, and that callback still reads q->timer (via snd_seq_check_queue()),
\nso q->timer must stay valid until it drains.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
ALSA: seq: close a re-opened queue timer in the destructor<\/p>\n
queue_delete() closes the queue timer, then frees it. snd_seq_timer_clo<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-5381","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/5381","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=5381"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5381"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5381"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}