Re: [PATCH]: Bug in ppc32 ld.so

On 10 May, Benjamin Herrenschmidt wrote:

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Hi Anton,

I saw:

http://sources.redhat.com/ml/libc-alpha/2002-05/msg00052.html

Thanks for posting that patch.  Have you by any chance alerted or sent
similar mail to YDL dev lists, Debian dev lists, SuSE dev lists, and
dev@linuxppc.

This would be a nasty bug to track down and those distributions may want to
know about this and get an udpated glibc-2.2.5 packages posted on their
sites for those brave users who are using later 2.4 kernels?

BTW, any idea when this change by Paul was introduced into the 2.4 kernel
series (specifically which 2.4.XX kernel?).

I submited a debian bug report with Anton message, Olaf (suse) is on
the linuxppc64 list and had the patch, YDL folks have or will have it
rsn (thanks to IRC magic ;)

just wait.

Well, I bet the guy who manage to actually _use_ such a hole is
probably an alien. I don't think you can seriously consider this
as a hole, but let's see how things go. In all cases, if that was
a security hole, then as Anton says, sparc64 and alpha are affected
too.

Let's fix ld.so, and separately see if the kernel bit is a security
hole or not.

Kaoru
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this is from geoffk

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This is a potential security hole, it'd be better to fix it in the kernel.

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From a performance viewpoint we do not want to icache synchronise all

zero pages we hand out. Its expensive. If a process creates code that
will be executed it should do the complete dcbst; sync; icbi; isync
sequence. I cant see how an application could gain information from a
stale icache, it cant read it.

It can run it and look at the result.  That may be all the information
it needs.

Suppose, for instance, a process has generated an decryption function
with the key embedded for performance reasons.  If this page gets
swapped to disk, and then zeroed and handed to another process, and is
still in the icache, then the new process has the ability to do a
decryption it wouldn't otherwise be able to do.  It could be possible,
under the right circumstances, for a malicious process to do this
intentionally.

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