In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
nfc: llcp: Fix list corruption \/ refcount desync in nfc_llcp_recv_dm()<\/p>\n
nfc_llcp_recv_dm() handles DM(NOBOUND)\/DM(REJ) for a socket that is still
\nlinked on local->connecting_sockets: it looks the socket up with
\nnfc_llcp_connecting_sock_get(), sets sk->sk_state = LLCP_CLOSED and
\nreturns, without taking the socket lock and without unlinking the socket
\nfrom the connecting_sockets list.<\/p>\n
llcp_sock_release() selects the list to unlink from by sk_state: a socket
\nin LLCP_CONNECTING is unlinked from connecting_sockets, otherwise from the
\nsockets list. Because recv_dm left the socket physically on
\nconnecting_sockets but in the LLCP_CLOSED state, release() takes the else
\nbranch and calls nfc_llcp_sock_unlink(&local->sockets, sk). That runs
\nsk_del_node_init() while holding sockets.lock, i.e. it removes the socket
\nfrom the connecting_sockets hlist under the wrong lock. A concurrent
\nconnect() linking another socket onto connecting_sockets under
\nconnecting_sockets.lock then mutates the same hlist unserialized, which
\ncorrupts the list and desyncs the sk_add_node()\/sk_del_node_init()
\nsock_hold()\/__sock_put() pairing. An unprivileged local process holding
\nLLCP sockets, with the DM supplied by the remote peer over an established
\nLLCP link, can drive this to leak kernel sockets without bound (the
\nmis-decrement goes through the non-freeing __sock_put() path, so the
\nobject is never released), leading to memory exhaustion \/ DoS.<\/p>\n
This is the same class of bug that was fixed in the sibling handler
\nnfc_llcp_recv_cc() by commit b493ea2765cc (“nfc: llcp: Fix use-after-free
\nrace in nfc_llcp_recv_cc()”); recv_dm did not receive the equivalent fix.<\/p>\n
Fix it the same way: take lock_sock(), re-check that the socket is still
\nhashed (release() may have won the race), and for the NOBOUND\/REJ case
\nunlink it from connecting_sockets before moving it to LLCP_CLOSED. The
\nunlink drops the connecting_sockets membership reference via
\nsk_del_node_init(), leaving the socket unhashed, so the later
\nnfc_llcp_sock_unlink() in llcp_sock_release() becomes a no-op and no
\ndouble put occurs.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
nfc: llcp: Fix list corruption \/ refcount desync in nfc_llcp_recv_dm()<\/p>\n
nfc_llcp_recv_dm() handles DM(NOBOUND)\/DM(REJ) for a socket<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-41053","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/41053","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=41053"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=41053"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=41053"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}