Re: [musl] [PATCH 0/1] ldso: continue searching if wrong architecture is found

[Markus Mayer <mmayer@broadcom.com>]

On Wed, 7 Feb 2024 at 10:09, Colin Cross <ccross@google.com> wrote:
>
> On Tue, Feb 6, 2024 at 5:23 PM Markus Mayer <mmayer@broadcom.com> wrote:
[...]
> > The problem:
> >
> > If LD_LIBRARY_PATH is set to a directory containing 32-bit libraries and
> > then a 64-bit binary is invoked, the shared library loader will pick up
> > the 32-bit version of a library first, because it'll look at
> > LD_LIBRARY_PATH before anything else. Mapping the 32-bit library into
> > the 64-bit process will fail. This much is expected.
> >
> > However, even though the correct library resides on the system, the
> > shared library loader never attempts to look for it. The 64-bit process
> > will fail to launch, even though there is no reason for the failure. The
> > problem only exists, because the shared library launcher doesn't look in
> > the remaining shared library directories.
> >
[...]
> > Continuing to search the system directories does seem to be the right
> > thing to do under the circumstances described here. Also, it is what
> > glibc does.
[...]
>
> There is a previous discussion of the same issue at
> https://www.openwall.com/lists/musl/2023/02/07/3.

Thanks, Colin, for pointing this out. This was very helpful.

We have been able to determine that Colin's patch series from February
2023 does address our issue. If I apply Colin's patches, the shared
library loader will continue searching for a shared library match
after unsuccessfully trying to load a 32-bit library into a 64-bit
process. This behaviour is just what one would expect. Consequently,
launching a 64-bit binary no longer fails just because the shared
library loader happens to find the 32-bit version of a library it
needs first.

In light of this, does it make sense to revive Colin's series from
last year and reconsider it for inclusion? If there is anything I can
do to facilitate the process, please let me know. I can certainly help
with testing.

If Colin's series is somehow not acceptable, please let me know as
well, and I will see what I can come up with to resolve the issue.

Thanks,
-Markus