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Message-ID: <4ADC292C.8010608@hitachi.com> Date: Mon, 19 Oct 2009 17:54:04 +0900 From: Tomoki Sekiyama <tomoki.sekiyama.qu@...achi.com> To: xiyou.wangcong@...il.com Cc: linux-kernel@...r.kernel.org, netdev@...r.kernel.org, alan@...rguk.ukuu.org.uk, davem@...emloft.net, satoshi.oshima.fk@...achi.com, hidehiro.kawai.ez@...achi.com, hideo.aoki.tk@...achi.com Subject: Re: [PATCH] AF_UNIX: Fix deadlock on connecting to shutdown socket Hi, thanks for testing! Américo Wang wrote: > On Mon, Oct 19, 2009 at 2:02 PM, Tomoki Sekiyama > <tomoki.sekiyama.qu@...achi.com> wrote: >> Hi, >> I found a deadlock bug in UNIX domain socket, which makes able to DoS >> attack against the local machine by non-root users. >> >> 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. >> >> PoC code: (Run as many times as cores on SMP machines.) Sorry for my ambiguous explanation ... > Interesting... > > I tried this with the following command: > > % for i in `seq 1 $(grep processor -c /proc/cpuinfo)`; > do ./unix-socket-dos-exploit; echo "=====$i====";done <snip> > My system doesn't hang at all. > > Am I missing something? > > Thanks! You should run the ./unix-socket-dos-exploit concurrently, like below: for i in {1..4} ; do ./unix-socket-dos-exploit & done # For safety reason, the PoC code stops in 15 seconds by alarm(15). -- Tomoki Sekiyama Linux Technology Center Hitachi, Ltd., Systems Development Laboratory E-mail: tomoki.sekiyama.qu@...achi.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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