In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
af_unix: Unify scc_index when finalising SCC in __unix_walk_scc().<\/p>\n
Commit bfdb01283ee8 (“af_unix: Assign a unique index to SCC.”)
\nchanged Tarjan’s algorithm to update lowlink with lowlink,
\nwhich is called lowpoint (unix_vertex.scc_index).<\/p>\n
unix_vertex_dead() assumes all vertices in an SCC share the same
\nlowpoint, but this is not always true if an SCC has two or more
\nback edges, depending on the order of DFS.<\/p>\n
For example, the graph below has two back edges from B to A
\nand from C to B.<\/p>\n
A –> B –> C
\n ^ | ^ |
\n `—-‘ `—-‘<\/p>\n
If DFS walks through A -> B -> C -> B (-> C -> B) -> A (-> B -> A),
\neach index and scc_index will be updated as follows.<\/p>\n
A –> B –> C C = (3, 3) (index, scc_index)
\n B = (2, 2)
\n A = (1, 1)<\/p>\n
A … B … C C = (3, 2)<-.
\n ^ | B = (2, 2) -'
\n `—-' A = (1, 1)<\/p>\n
A … B … C C = (3, 2)
\n ^ | . . B = (2, 1) B –> C
\n ^ | ^ |
\n `—-‘ `—-‘
\n 2 4<\/p>\n
Let’s unify scc_index across the SCC when finalising it.<\/p>\n
Note that updating v->index was previously done in unix_scc_dead(),
\nwhen called from __unix_walk_scc(), just to save one loop. Since
\n__unix_walk_scc() now iterates over the SCC anyway, the update is
\nmoved back to __unix_walk_scc() and ‘fast’ argument is dropped.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
af_unix: Unify scc_index when finalising SCC in __unix_walk_scc().<\/p>\n
Commit bfdb01283ee8 (“af_unix: Assign a unique index to SCC.”)<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-33358","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/33358","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=33358"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=33358"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=33358"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}