In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
af_unix: Update last skb marker in manage_oob().<\/p>\n
Fahad Alharbi reported that blocking recv(MSG_PEEK) could hog CPU
\ndue to OOB skb.<\/p>\n
In the following cases, manage_oob() skips OOB skb(s) and returns
\nNULL for the last recv(MSG_PEEK):<\/p>\n
socketpair(AF_UNIX, SOCK_STREAM, 0, sk);<\/p>\n
1) skb -> OOB skb -> NULL
\n send(sk[0], “ab”, 2, MSG_OOB);
\n recv(sk[1], buf, 0, MSG_PEEK);<\/p>\n
2) skb -> consumed OOB skb -> NULL
\n send(sk[0], “ab”, 2, MSG_OOB);
\n recv(sk[1], buf, 1, MSG_OOB);
\n recv(sk[1], buf, 0, MSG_PEEK);<\/p>\n
3) consumed OOB skb -> OOB skb -> NULL
\n send(sk[0], “a”, 1, MSG_OOB);
\n recv(sk[1], buf, 0, MSG_OOB);
\n send(sk[0], “b”, 1, MSG_OOB);
\n recv(sk[1], buf, 1, MSG_PEEK);<\/p>\n
Then, @copied is 0 in unix_stream_read_generic() (zero-length buffer,
\nor non-OOB skb is not yet consumed), and unix_stream_data_wait() is
\ncalled.<\/p>\n
However, it returns immediately because @last is not updated in
\nunix_stream_read_generic(), and the thread busy-waits for a new skb.<\/p>\n
Let’s update @last in manage_oob().<\/p>\n
For MSG_PEEK, @last is updated with the skipped OOB, and for the
\nnon-peek case, @last matches the returned value (when !copied)
\nbecause OOB is unlinked.<\/p>\n
Note that manage_oob() is inlined and no stack canary is added.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
af_unix: Update last skb marker in manage_oob().<\/p>\n
Fahad Alharbi reported that blocking recv(MSG_PEEK) could hog CPU
\ndue to OOB skb.<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-29141","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/29141","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=29141"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=29141"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=29141"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}