In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
tracing: Undo the registration when enabling the histogram trigger fails<\/p>\n
Commit 6f86bdeab633 (“tracing: Fix bad hist from corrupting named_triggers
\nlist”) described how a trigger that is registered but not on file->triggers
\nends up freed while still on the global named_triggers list, and moved the
\nregistration down so that hist_trigger_enable() follows it immediately. One
\npath still gets there. hist_trigger_enable() adds the trigger and takes it
\nstraight back out when the event cannot be enabled:<\/p>\n
\tlist_add_tail_rcu(&data->list, &file->triggers);<\/p>\n
\tupdate_cond_flag(file);<\/p>\n
\tif (trace_event_trigger_enable_disable(file, 1) list);
\n\t\tupdate_cond_flag(file);
\n\t\tret–;
\n\t}<\/p>\n
so the list walk in hist_unregister_trigger() matches nothing, test stays
\nNULL, and the ->free() that would call del_named_trigger() is skipped.
\nout_unreg falls through to out_free, which frees the trigger anyway:<\/p>\n
BUG: KASAN: slab-use-after-free in find_named_trigger+0xac\/0xc0
\n Read of size 8 at addr ffff8880091d3160 by task init\/1
\n find_named_trigger+0xac\/0xc0
\n hist_register_trigger+0xc1\/0xa00
\n event_hist_trigger_parse+0x3146\/0x6af0
\n event_trigger_write+0xce\/0x160
\n Freed by task 69:
\n kfree+0x154\/0x420
\n trigger_kthread_fn+0xfd\/0x160<\/p>\n
Leave the trigger where hist_unregister_trigger() can find it and let that
\nundo the registration, which is the only code that knows all of what
\ncmd_ops->init() took: the named list entry, the hist_pad reference, the
\nreference on the trigger a named histogram is shared with, and the copied
\ncmd_ops. It also pairs the failed trace_event_trigger_enable_disable(),
\nwhose sm_ref and buffered event reference are otherwise left behind.<\/p>\n
Since ->free() releases trigger_data and, for a trigger that does not share
\nits histogram, hist_data with it, out_unreg can no longer fall through to
\nout_free. For a trigger that does share, hist_register_trigger() has
\nalready destroyed the caller’s hist_data, so the fall-through was reading
\nfreed memory there as well.<\/p>\n
Move the enable_timestamps check in hist_unregister_trigger() above the
\n->free() call for the same reason: hist_data does not outlive it once the
\ntrigger being removed is the one that owns it.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
tracing: Undo the registration when enabling the histogram trigger fails<\/p>\n
Commit 6f86bdeab633 (“tracing: Fix bad hist from corrupti<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-29074","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/29074","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=29074"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=29074"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=29074"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}