[lkml]   [2009]   [Oct]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [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
> <> 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
> 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
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2009-10-19 10:57    [W:0.060 / U:2.984 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site