In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
hwmon: (hp-wmi-sensors) Fix use-after-free in fungible_show()<\/p>\n
nsensor->current_state is dynamically replaced as the sensor’s state
\nchanges. update_numeric_sensor_from_wobj() does this by freeing the
\nold string and installing a new one:<\/p>\n
\tif (strcmp(trimmed, nsensor->current_state)) {
\n\t\tnew_string = hp_wmi_strdup(dev, trimmed);
\n\t\tif (new_string) {
\n\t\t\tdevm_kfree(dev, nsensor->current_state);
\n\t\t\tnsensor->current_state = new_string;
\n\t\t}
\n\t}<\/p>\n
This function is only ever called from hp_wmi_update_info() while
\nstate->lock is held, so the free-and-replace itself is properly
\nserialized against concurrent updates.<\/p>\n
fungible_show(), however, reads the same pointer after the lock has
\nalready been dropped:<\/p>\n
\terr = hp_wmi_update_info(state, info);
\n\tif (err)
\n\t\treturn err;<\/p>\n
\tswitch (prop) {
\n\t…
\n\tcase HP_WMI_PROPERTY_CURRENT_STATE:
\n\t\tseq_printf(seqf, “%sn”, nsensor->current_state);
\n\t\tbreak;<\/p>\n
hp_wmi_update_info() takes state->lock internally and releases it
\nbefore returning, so by the time fungible_show() dereferences
\nnsensor->current_state in seq_printf(), no lock is held. Two
\nprocesses reading a sensor’s current_state debugfs entry at
\noverlapping times (or one reading it while another read of the same
\nsensor triggers a refresh) can race: one thread’s seq_printf() can
\nbe part-way through printing the string at the moment another
\nthread’s call into update_numeric_sensor_from_wobj() frees it with
\ndevm_kfree() and installs a new pointer, causing a use-after-free
\nread.<\/p>\n
Take state->lock around the read in fungible_show() as well, so it
\ncan never run concurrently with the free-and-replace in
\nupdate_numeric_sensor_from_wobj().<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
hwmon: (hp-wmi-sensors) Fix use-after-free in fungible_show()<\/p>\n
nsensor->current_state is dynamically replaced as the sensor’s state<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-33269","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/33269","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=33269"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=33269"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=33269"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}