Date: Fri, 16 Dec 2005 17:10:16 +0200 From: Kostik Belousov <kostikbel@gmail.com> To: Csaba Henk <csaba-ml@creo.hu> Cc: freebsd-current@freebsd.org Subject: Re: Easy DoS Message-ID: <20051216151016.GE84442@deviant.zoral.local> In-Reply-To: <20051216133448.GA10382@beastie.creo.hu> References: <20051216133448.GA10382@beastie.creo.hu>
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On Fri, Dec 16, 2005 at 02:34:48PM +0100, Csaba Henk wrote:
> Do
>=20
> echo 'main() { write(1, 0, 1); }' > edos.c
> gcc -o edos edos.c
> ./edos | cat
>=20
> ... and now the edos process gets stuck in the write syscall, unkillably,
> keeping the CPU spinning. (Seen on my 6.0-RELEASE and 7.0-CURRENT boxen.)
>=20
> Is it a bug or a feature?
>=20
> Csaba
Sure, it is a bug :).
Please, try the following patch (against 7-CURRENT,
shall work for 6-STABLE too):
--- src-pristine/sys/kern/sys_pipe.c Mon Jul 11 11:33:58 2005
+++ src-quotas/sys/kern/sys_pipe.c Fri Dec 16 17:03:01 2005
@@ -1176,6 +1176,8 @@
("Pipe buffer overflow"));
}
pipeunlock(wpipe);
+ if (error !=3D 0)
+ break;
} else {
/*
* If the "read-side" has been blocked, wake it up =
now.
Best regards,
Kostik Belousov
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