From: Nuno Monteiro <nuno@itsari.org>
To: Gianni Tedesco <gianni@scaramanga.co.uk>
Cc: marcelo.tosatti@cyclades.com, linux-kernel@vger.kernel.org
Subject: Re: Local DoS attack on i386 (was: new kernel bug)
Date: Mon, 14 Jun 2004 15:20:01 +0100 [thread overview]
Message-ID: <20040614142001.GA3032@hobbes.itsari.int> (raw)
In-Reply-To: <1087221517.3375.3.camel@sherbert> (from gianni@scaramanga.co.uk on Mon, Jun 14, 2004 at 14:58:37 +0100)
On 2004.06.14 14:58, Gianni Tedesco wrote:
> On Sat, 2004-06-12 at 11:59 +0200, Manuel Arostegui Ramirez wrote:
> > Somebody know a patch to solved this new bug?
> > http://reviewed.homelinux.org/news/2004-06-11_kernel_crash/index.html.en
> > Affected versions:
> > * Linux 2.6.x
> > o Linux 2.6.7-rc2
> > o Linux 2.6.6 (all versions)
> > o Linux 2.6.6 SMP (verified by riven)
> > o Linux 2.6.5-gentoo (verified by RatiX)
> > o Linux 2.6.5-mm6 - (verified by Mariux)
> > * Linux 2.4.2x
> > o Linux 2.4.26 vanilla
> > o Linux 2.4.26-rc1 vanilla
> > o Linux 2.4.26-gentoo-r1
> > o Linux 2.4.22
>
> Seems to be a scheduler race or something?
>
This was already fixed in 2.6, see http://linux.bkbits.net:8080/linux-2.5/diffs/include/asm-i386/i387.h@1.16?nav=index.html|src/.|src/include|src/include/asm-i386|hist/include/asm-i386/i387.h
The same fix should be applied to 2.4. I'm running locally a very
hacked version of 2.4.22 with it and it survives that crash.c program.
Here's the diff. Marcelo, please merge.
--- linux-2.4.27-pre5/include/asm-i386/i387.h~fix-x86-clear_fpu-macro 2004-06-14 15:12:13.909059344 +0100
+++ linux-2.4.27-pre5/include/asm-i386/i387.h 2004-06-14 15:12:45.970185312 +0100
@@ -34,7 +34,7 @@ extern void kernel_fpu_begin(void);
#define clear_fpu( tsk ) do { \
if ( tsk->flags & PF_USEDFPU ) { \
- asm volatile("fwait"); \
+ asm volatile("fnclex ; fwait"); \
tsk->flags &= ~PF_USEDFPU; \
stts(); \
} \
next prev parent reply other threads:[~2004-06-14 14:23 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-06-12 9:59 new kernel bug Manuel Arostegui Ramirez
2004-06-12 12:33 ` Kalin KOZHUHAROV
2004-06-12 12:42 ` Manuel Arostegui Ramirez
2004-06-12 13:37 ` David Connolly
2004-06-12 15:08 ` Han Boetes
2004-06-12 15:08 ` Manuel Arostegui Ramirez
2004-06-14 13:58 ` Local DoS attack on i386 (was: new kernel bug) Gianni Tedesco
2004-06-14 14:05 ` Gianni Tedesco
2004-06-14 14:08 ` Manuel Arostegui Ramirez
2004-06-14 14:20 ` Nuno Monteiro [this message]
2004-06-14 14:59 ` Manuel Arostegui Ramirez
2004-06-15 4:34 ` Local DoS attack on i386 Andre Tomt
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