In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
fsnotify: Fix stale object mask after concurrent mark updates<\/p>\n
When a mark gets a new event bit, fanotify and inotify may avoid
\nrecalculating the object mask if the cached aggregate already contains that
\nbit. This is racy with a recalculation triggered by a concurrent update to
\nanother mark on the same connector.<\/p>\n
The concurrent scan can read the mark before the new bit is added, while
\nthe updater reads the old aggregate before that scan publishes its result.
\nThe updater then skips recalculation and the scan publishes a mask without
\nthe bit, leaving the object mask stale after both updates complete.<\/p>\n
This can be reproduced with two fanotify groups watching the same inode:
\none thread removes FAN_MODIFY from one existing mark while another thread
\nadds FAN_MODIFY to the other mark. After both fanotify_mark() calls return,
\nwrites can fail to produce FAN_MODIFY for the group whose mark now contains
\nthe bit. This was reproduced on an unmodified v6.12.95 kernel. The
\nequivalent inotify interleaving loses IN_MODIFY events.<\/p>\n
For normal fanotify additions, recalculate whenever the raw mark mask
\nchanges. The normal mask is not cleared asynchronously, so an unchanged
\naddition cannot introduce missing interest. Always recalculate ignore-mask
\nupdates because FS_MODIFY handling may clear the ignore mask without taking
\nmark->lock, making snapshot comparisons unreliable.<\/p>\n
Always recalculate after updating an existing inotify watch. Its replace
\npath temporarily sets mark->mask to zero, so a concurrent scan can observe
\nzero even when the old and final masks are equal. Assigning the replacement
\nmask directly would avoid the transient zero, but existing-watch updates
\nare infrequent, so unconditional recalculation is simpler.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
fsnotify: Fix stale object mask after concurrent mark updates<\/p>\n
When a mark gets a new event bit, fanotify and inotify may avoid
\nrec<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-21517","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/21517","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=21517"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=21517"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=21517"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}