In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
afs: Fix the locking used by afs_get_link()<\/p>\n
The afs filesystem in the kernel doesn’t do locking correctly for symbolic
\nlinks. There are a number of problems:<\/p>\n
(1) It doesn’t do any locking around afs_read_single() to prevent races
\n between multiple ->get_link() calls, thereby allowing the possibility
\n of leaks.<\/p>\n
(2) It doesn’t use RCU barriering when accessing the buffer pointers
\n during RCU pathwalk.<\/p>\n
(3) It can race with another thread updating the contents of the symlink
\n if a third party updated it on the server.<\/p>\n
Fix this by the following means:<\/p>\n
(0) Move symlink handling into its own file as this makes it more
\n complicated.<\/p>\n
(1) Take the validate_lock around afs_read_single() to prevent races
\n between multiple ->get_link() calls.<\/p>\n
(2) Keep a separate copy of the symlink contents with an rcu_head. This
\n is always going to be a lot smaller than a page, so it can be
\n kmalloc’d and save quite a bit of memory. It also needs a refcount
\n for non-RCU pathwalk.<\/p>\n
(3) Split the symlink read and write-to-cache routines in afs from those
\n for directories.<\/p>\n
(4) Discard the I\/O buffer as soon as the write-to-cache completes as this
\n is a full page (plus a folio_queue).<\/p>\n
(5) If there’s no cache, discard the I\/O buffer immediately after reading
\n and copying if there is no cache.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
afs: Fix the locking used by afs_get_link()<\/p>\n
The afs filesystem in the kernel doesn’t do locking correctly for symbolic
\nlinks. The<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-15044","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/15044","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=15044"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=15044"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=15044"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}