In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
ALSA: timer: Clear SNDRV_TIMER_IFLG_DEAD once the close completes<\/p>\n
snd_timer_close_locked() marks an instance with SNDRV_TIMER_IFLG_DEAD
\nand returns early when the flag is already set, but the flag is never
\ncleared again. A completed close ends in remove_slave_links(), which
\nleaves timeri->timer NULL, so a second close is already harmless through
\nthe timer == NULL path; the early return can only be reached by an
\ninstance that was opened again in between. For such an instance the
\nclose unlinks nothing, so snd_timer_instance_free() frees an object that
\nis still on timer->open_list_head, still on snd_timer_master_list if it
\nwas opened with a slave key, still owns any adopted slaves, and still
\nholds its timer and module references.<\/p>\n
snd_seq_timer_open() reopens an instance exactly like that: it retries
\nits fallback open on the same object after a failure that has already
\nrun snd_timer_close_locked() internally. An unprivileged user with
\naccess to \/dev\/snd\/timer and \/dev\/snd\/seq can force that failure, since
\nsnd_timer_check_master() returns -EBUSY when a pending slave matches the
\nnew master’s (slave_class, slave_id) key and the target timer has
\nreached max_instances, and SNDRV_TIMER_IOCTL_SELECT with dev_class =
\nSNDRV_TIMER_CLASS_SLAVE keeps the caller-supplied dev_sclass, so a
\nsequencer queue’s key can be forged. The freed instance is afterwards
\ndereferenced by any further snd_timer_open() on that timer, by
\nsnd_timer_check_slave(), and by \/proc\/asound\/timers, which faults on the
\nstale ti->owner pointer.<\/p>\n
The flag only has to be visible while the close is in progress, which is
\nall its other users need. Clear it in remove_slave_links(), under the
\nsame timer->lock that sets it, once the instance is off every list.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
ALSA: timer: Clear SNDRV_TIMER_IFLG_DEAD once the close completes<\/p>\n
snd_timer_close_locked() marks an instance with SNDRV_TIMER_IFLG<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-7496","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/7496","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=7496"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=7496"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=7496"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}