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Bug#300119: libc6: LD_DEBUG=versions can lead to segmentation fault

At Thu, 17 Mar 2005 14:29:14 -0500,
John Denker wrote:
> 1) I compiled /usr/lib/libpng12.so.0 aka libpng12.so. from
> sources and installed it.  Symptoms are the same using the Debian 
> source package or the tarball from libpng.org.
> 2) As a tangential issue:  Many programs (even ones like "vi", for 
> which it doesn't make much sense) now issue the warning
>   /usr/lib/libpng12.so.0: no version information available (required by ...)
> which is pretty weird;  why does "vi" depend on libpng anyway?
> I note in passing that the libpng makefile tries to set some
> version information with -soname, and I don't understand why
> that isn't good enough .... but that is *not* the bug I wish to 
> emphasize at the moment.

But your build may be broken.

> 3) In the attempt to debug the tangential issue, I tried using
> LD_DEBUG=versions.  What a disaster.  Any program that
> previously issued a warning now segfaults.  For example:
>   LD_DEBUG=versions vi
> [snip]
>   12633:     checking for version `GLIBC_2.0' in file /lib/libgcc_s.so.1 required by file /usr/lib/libqt-mt.so.3
>   12633:     checking for version `PNG12_0' in file /usr/lib/libpng12.so.0 required by file /usr/lib/libqt-mt.so.3
>   Segmentation fault
> Bottom line:  I don't know what (if anything) is wrong with
> libpng12 ... but no matter what, it shouldn't cause ld.so
> to segfault.  Wild memory references often lead to sneaky
> security problems, not to mention the obvious loss of functionality.

ldd tells you which libraries will be used.  Then check what
/usr/lib/libqt-mt.so.3 is.

-- gotom

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