In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
vsock: don’t check the listener’s sk_err in vsock_accept()<\/p>\n
Syzbot reported an issue which can be reproduced with these steps:
\n\tr0 = socket(AF_VSOCK, SOCK_STREAM, 0)
\n\tbind(r0, {VMADDR_CID_ANY, PORT})
\n\tconnect(r0, {VMADDR_CID_LOCAL, PORT}) -> -1, EPROTO (self-connect)
\n\tlisten(r0, backlog) -> 0
\n\tr1 = socket(AF_VSOCK, SOCK_STREAM, 0)
\n\tconnect(r1, {VMADDR_CID_LOCAL, PORT}) -> 0
\n\taccept(r0) -> -1, EPROTO (stale sk_err)<\/p>\n
Basically, it creates a socket (r0) and triggers a self-connect after
\nbinding it. This self-connect fails with EPROTO because it loops back
\nto r0 while the socket is still in the TCP_SYN_SENT state, causing it
\nto be incorrectly dispatched to the connecting-client path. The
\nunexpected packet type encountered there sets sk_err to EPROTO.<\/p>\n
After that, it invokes a listen() call on the same socket. This
\nlisten() call succeeds because the kernel’s listening path never
\ninspects or clears sk_err. Then, a new socket (r1) is created as a
\nnormal client and connects to r0. However, vsock_accept() rejects this
\nincoming connection because the listener’s sk_err still holds the
\nEPROTO error from the earlier failed self-connect.<\/p>\n
This rejection causes the child socket created for r1’s connection to
\nnever be freed on virtio or hyperv transports; only the VMCI transport
\nimplements pending_work to revisit and clean up a rejected socket.<\/p>\n
For a non-blocking connect(), vsock_connect() may return -EINPROGRESS
\nimmediately, and vsock_connect_timeout() can later set sk->sk_err
\nasynchronously.<\/p>\n
Since no vsock transport ever sets sk_err on a socket while it is in
\nTCP_LISTEN state, checking it in vsock_accept() serves no purpose and
\nonly carries forward errors left behind by earlier, unrelated
\nconnection attempts on the same socket. Remove the checks so accept()
\nno longer rejects valid incoming connections because of a stale
\nerror, which also avoids the resource leak described above.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
vsock: don’t check the listener’s sk_err in vsock_accept()<\/p>\n
Syzbot reported an issue which can be reproduced with these steps:
\n\tr0 <\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-25547","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/25547","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=25547"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=25547"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=25547"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}