[PATCH] getsockopt() early argument sanity checking

Willy,

I propose the attached patch (extracted from 2.4.33-ow1) for inclusion
into 2.4.34-pre.

(2.6 kernels could benefit from the same change, too, but at the moment
I am dealing with proper submission of generic changes like this that
are a part of 2.4.33-ow1.)

The patch makes getsockopt(2) sanity-check the value pointed to by
the optlen argument early on.  This is a security hardening measure
intended to prevent exploitation of certain potential vulnerabilities in
socket type specific getsockopt() code on UP systems.

This change has been a part of -ow patches for some years.

Thanks,

-- 
Alexander Peslyak <solar at openwall.com>
GPG key ID: B35D3598  fp: 6429 0D7E F130 C13E C929  6447 73C3 A290 B35D 3598
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