From: "Petr Vandrovec" <VANDROVE@vc.cvut.cz>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: RE: FW: i386 Linux kernel DoS (clarification)
Date: Wed, 13 Nov 2002 22:18:32 +0100 [thread overview]
Message-ID: <76D1FF66BB6@vcnet.vc.cvut.cz> (raw)
On 13 Nov 02 at 21:36, Alan Cox wrote:
> Try this
>
> (In the Linus Torvalds tradition its not tested)
I'll test it, but before kernel compiles...
> --- arch/i386/kernel/entry.S~ 2002-11-13 21:30:37.000000000 +0000
> +++ arch/i386/kernel/entry.S 2002-11-13 21:29:47.000000000 +0000
> @@ -126,6 +126,7 @@
> ENTRY(lcall7)
> pushfl # We get a different stack layout with call
> # gates, which has to be cleaned up later..
> + andl $~0x4500, (%esp) # Clear NT since we are doing an iret
this will clear 'D' and 'T' in caller after we do
iret (if lcall7 returns, of course). I'm not sure that callers
expect that.
> @@ -390,6 +392,9 @@
> pushl $do_divide_error
> ALIGN
> error_code:
> + pushfl
> + andl $~0x4500, (%esp) # NT must be clear, do a cld for free
> + popfl
I believe that NT should be automagically cleared by int.
Best regards,
Petr Vandrovec
vandrove@vc.cvut.cz
next reply other threads:[~2002-11-13 21:14 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-11-13 21:18 Petr Vandrovec [this message]
2002-11-13 21:48 ` FW: i386 Linux kernel DoS (clarification) Alan Cox
2002-11-13 21:51 ` Petr Vandrovec
2002-11-14 3:41 ` Andrea Arcangeli
-- strict thread matches above, loose matches on Subject: below --
2002-11-13 20:36 Petr Vandrovec
2002-11-13 21:10 ` Alan Cox
2002-11-13 21:13 ` Petr Vandrovec
2002-11-13 21:47 ` Alan Cox
2002-11-13 20:23 Leif Sawyer
2002-11-13 21:36 ` Alan Cox
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