Date: Mon, 19 Oct 2009 15:27:31 -0400 (EDT) From: Josh Bressers <bressers@...hat.com> To: oss-security@...ts.openwall.com Cc: "Steven M. Christey" <coley@...us.mitre.org> Subject: Re: CVE request: kernel: AF_UNIX: Fix deadlock on connecting to shutdown socket Please use CVE-2009-3621. Thanks. -- JB ----- "Eugene Teo" <eugeneteo@...nel.sg> wrote: > Quoting from the patch submitted: > "...a deadlock bug in UNIX domain socket, which makes able to DoS > attack against the local machine by non-root users. > > ... > Why this happens: > Error checks between unix_socket_connect() and unix_wait_for_peer() > are > inconsistent. The former calls the latter to wait until the backlog > is > processed. Despite the latter returns without doing anything when > the > socket is shutdown, the former doesn't check the shutdown state and > just retries calling the latter forever." > > How to reproduce: > 1. Make a listening AF_UNIX/SOCK_STREAM socket with an abstruct > namespace(*), and shutdown(2) it. > 2. Repeat connect(2)ing to the listening socket from the other > sockets > until the connection backlog is full-filled. > 3. connect(2) takes the CPU forever. If every core is taken, the > system hangs. > > Reproducer: > http://patchwork.kernel.org/patch/54678/ > > You will need to add in the missing header files: > #include <string.h> > #include <stdio.h> > #include <sys/un.h> > #include <sys/types.h> > #include <sys/socket.h> > > Reference: > https://bugzilla.redhat.com/show_bug.cgi?id=529626 > > Thanks, Eugene
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