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Re: ld.so bug - LD_DEBUG_OUTPUT follows symlinks
From: Robert Bihlmeyer <robbe () ORCUS PRIV AT>
Date: Thu, 28 Sep 2000 17:58:27 +0200

"Dwayne C . Litzenberger" <dlitz () CHEERFUL COM> writes:

On Tue, Sep 26, 2000 at 02:11:12AM +0200, Jakub Vlasek wrote:
   ld.so from glibc2 doesn't unset variables LD_DEBUG_OUTPUT and LD_DEBUG
when running suid. If program calls setuid(0) and then fork(), child
process will follow prepared symlink ($LD_DEBUG_OUTPUT.$pid) and
overwrites any file in system.

When I run the suid program, LD_DEBUG still works (odd, but true), but
LD_DEBUG_OUTPUT seems to be ignored (output goes to the terminal).

The problem is not the suid program, but another program exec'd by the
suid program with uid==euid. In this case the glibc security checks
are off and the inherited LD_DEBUG_OUTPUT is again used.


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