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<a href="https://gitlab.com/ldalessa" style="color: #1068bf;">Luke D'Alessandro</a> created an issue: <a href="https://gitlab.com/gnutls/gnutls/-/issues/1398" style="color: #1068bf;">#1398</a>
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<h2 dir="auto" style="font-size: 1.5em; font-weight: 600; padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-color: #eaeaea; border-bottom-style: solid; color: #303030; margin: 0 0 16px;" align="initial">
<a id="user-content-description-of-problem" class="anchor" href="#description-of-problem" aria-hidden="true" style="color: #1068bf; margin-top: 0; float: left; margin-left: -20px; text-decoration: none; outline: none;"></a>Description of problem:</h2>
<p dir="auto" style="color: #303030; margin: 0 0 16px;" align="initial">The GMP library indirects dynamic memory allocation through a couple of function pointers, and allows client code to get and set those values through calls to <code style='font-size: 90%; color: #1f1f1f; word-wrap: break-word; background-color: #f0f0f0; border-radius: 4px; margin-top: 0; font-weight: inherit; font-family: "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; white-space: pre-wrap; overflow-wrap: break-word; word-break: keep-all; padding: 2px 4px;'>mp_set_memory_functions()</code>. <a href="https://gitlab.com/gnutls/gnutls/-/commit/41c9c845a342359327403431050d3458246896af" data-original="41c9c845" data-link="false" data-link-reference="false" data-project="179611" data-commit="41c9c845a342359327403431050d3458246896af" data-reference-type="commit" data-container="body" data-placement="top" title="Use custom allocators for GMP to make sure temporary secrets" class="gfm gfm-commit has-tooltip" style='color: #1068bf; font-family: "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-size: 95%;'>41c9c845</a> introduced code into <code style='font-size: 90%; color: #1f1f1f; word-wrap: break-word; background-color: #f0f0f0; border-radius: 4px; font-weight: inherit; font-family: "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; white-space: pre-wrap; overflow-wrap: break-word; word-break: keep-all; padding: 2px 4px;'>gnutls_crypto_init</code> that leverages this functionality to replace GMP's realloc and free functions to use <code style='font-size: 90%; color: #1f1f1f; word-wrap: break-word; background-color: #f0f0f0; border-radius: 4px; font-weight: inherit; font-family: "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; white-space: pre-wrap; overflow-wrap: break-word; word-break: keep-all; padding: 2px 4px;'>gnutls_realloc_zero</code> and <code style='font-size: 90%; color: #1f1f1f; word-wrap: break-word; background-color: #f0f0f0; border-radius: 4px; font-weight: inherit; font-family: "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; white-space: pre-wrap; overflow-wrap: break-word; word-break: keep-all; padding: 2px 4px;'>gnutls_free_zero</code>.</p>
<p dir="auto" style="color: #303030; margin: 0 0 16px;" align="initial">I have some static global <code style='font-size: 90%; color: #1f1f1f; word-wrap: break-word; background-color: #f0f0f0; border-radius: 4px; margin-top: 0; font-weight: inherit; font-family: "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; white-space: pre-wrap; overflow-wrap: break-word; word-break: keep-all; padding: 2px 4px;'>mpq_class</code> objects (using GMP's C++ API) that have their destructors run in <code style='font-size: 90%; color: #1f1f1f; word-wrap: break-word; background-color: #f0f0f0; border-radius: 4px; font-weight: inherit; font-family: "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; white-space: pre-wrap; overflow-wrap: break-word; word-break: keep-all; padding: 2px 4px;'>__run_exit_handlers</code>, after <code style='font-size: 90%; color: #1f1f1f; word-wrap: break-word; background-color: #f0f0f0; border-radius: 4px; font-weight: inherit; font-family: "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; white-space: pre-wrap; overflow-wrap: break-word; word-break: keep-all; padding: 2px 4px;'>main()</code>. These destructors attempt to use GMP's <code style='font-size: 90%; color: #1f1f1f; word-wrap: break-word; background-color: #f0f0f0; border-radius: 4px; font-weight: inherit; font-family: "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; white-space: pre-wrap; overflow-wrap: break-word; word-break: keep-all; padding: 2px 4px;'>__gmp_free_func</code> to free their data, which was set to <code style='font-size: 90%; color: #1f1f1f; word-wrap: break-word; background-color: #f0f0f0; border-radius: 4px; font-weight: inherit; font-family: "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; white-space: pre-wrap; overflow-wrap: break-word; word-break: keep-all; padding: 2px 4px;'>gnutls_free_zero</code>, however due to the vagaries of shared-object ctor/dtor ordering, libgnutls.so has <strong style="font-weight: bold;">already been unloaded</strong> and thus that call segfaults.</p>
<p dir="auto" style="color: #303030; margin: 0 0 16px;" align="initial">I do not personally load libgnutls, that is done transitively by OpenMPI in this case.</p>
<p dir="auto" style="color: #303030; margin: 0 0 16px;" align="initial">As an end user, I don't really know of a great way to workaround this. I can manually reset GMP's pointers to their default after gnutls resets them now that I know this is a problem. I think the fix might be to have gnutls remember these values and reset them during <code style='font-size: 90%; color: #1f1f1f; word-wrap: break-word; background-color: #f0f0f0; border-radius: 4px; margin-top: 0; font-weight: inherit; font-family: "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; white-space: pre-wrap; overflow-wrap: break-word; word-break: keep-all; padding: 2px 4px;'>deinit()</code>, but that assumes everyone is correctly calling that function.</p>
<h2 dir="auto" style="font-size: 1.5em; font-weight: 600; padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-color: #eaeaea; border-bottom-style: solid; color: #303030; margin: 24px 0 16px;" align="initial">
<a id="user-content-version-of-gnutls-used" class="anchor" href="#version-of-gnutls-used" aria-hidden="true" style="color: #1068bf; margin-top: 0; float: left; margin-left: -20px; text-decoration: none; outline: none;"></a>Version of gnutls used:</h2>
<h2 dir="auto" style="font-size: 1.5em; font-weight: 600; padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-color: #eaeaea; border-bottom-style: solid; color: #303030; margin: 24px 0 16px;" align="initial">
<a id="user-content-distributor-of-gnutls-eg-ubuntu-fedora-rhel" class="anchor" href="#distributor-of-gnutls-eg-ubuntu-fedora-rhel" aria-hidden="true" style="color: #1068bf; margin-top: 0; float: left; margin-left: -20px; text-decoration: none; outline: none;"></a>Distributor of gnutls (e.g., Ubuntu, Fedora, RHEL)</h2>
<p dir="auto" style="color: #303030; margin: 0 0 16px;" align="initial">Various means, this occurs on all platforms that I run on.</p>
<h2 dir="auto" style="font-size: 1.5em; font-weight: 600; padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-color: #eaeaea; border-bottom-style: solid; color: #303030; margin: 24px 0 16px;" align="initial">
<a id="user-content-how-reproducible" class="anchor" href="#how-reproducible" aria-hidden="true" style="color: #1068bf; margin-top: 0; float: left; margin-left: -20px; text-decoration: none; outline: none;"></a>How reproducible:</h2>
<p dir="auto" style="color: #303030; margin: 0 0 16px;" align="initial">Forgive me, I don't know how to actually call any functions in gnutls, but the following code reproduces the problem when compiled with mpic++.</p>
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<pre class="code highlight js-syntax-highlight language-plaintext" lang="plaintext" data-canonical-lang="C++" v-pre="true" style='display: block; font-size: 13px; color: #303030; line-height: 1.6em; overflow-x: auto; border-radius: 2px; position: relative; font-family: "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; word-break: break-all; word-wrap: break-word; background-color: #fafafa; margin: 0 0 16px; padding: 12px; border: 1px solid #dbdbdb;'><code style='font-size: inherit; color: inherit; word-wrap: normal; word-break: keep-all; background-color: inherit; border-radius: 4px; white-space: pre; margin-top: 0; font-family: "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; overflow-wrap: normal; padding: unset;'><span id="LC1" class="line" lang="plaintext" style="margin-top: 0;">#include <gmpxx.h></span>
<span id="LC2" class="line" lang="plaintext">#include <mpi.h></span>
<span id="LC3" class="line" lang="plaintext"></span>
<span id="LC4" class="line" lang="plaintext">static mpq_class _;</span>
<span id="LC5" class="line" lang="plaintext"></span>
<span id="LC6" class="line" lang="plaintext">int main()</span>
<span id="LC7" class="line" lang="plaintext">{</span>
<span id="LC8" class="line" lang="plaintext"> MPI_Init(NULL, NULL);</span>
<span id="LC9" class="line" lang="plaintext"> MPI_Finalize();</span>
<span id="LC10" class="line" lang="plaintext">}</span></code></pre>
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<h2 dir="auto" style="font-size: 1.5em; font-weight: 600; padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-color: #eaeaea; border-bottom-style: solid; color: #303030; margin: 24px 0 16px;" align="initial">
<a id="user-content-actual-results" class="anchor" href="#actual-results" aria-hidden="true" style="color: #1068bf; margin-top: 0; float: left; margin-left: -20px; text-decoration: none; outline: none;"></a>Actual results:</h2>
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<pre class="code highlight js-syntax-highlight language-plaintext" lang="plaintext" data-canonical-lang="" v-pre="true" style='display: block; font-size: 13px; color: #303030; line-height: 1.6em; overflow-x: auto; border-radius: 2px; position: relative; font-family: "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; word-break: break-all; word-wrap: break-word; background-color: #fafafa; margin: 0 0 16px; padding: 12px; border: 1px solid #dbdbdb;'><code style='font-size: inherit; color: inherit; word-wrap: normal; word-break: keep-all; background-color: inherit; border-radius: 4px; white-space: pre; margin-top: 0; font-family: "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; overflow-wrap: normal; padding: unset;'><span id="LC1" class="line" lang="plaintext" style="margin-top: 0;">ldalessa@portland:~/temp$ mpic++ -o test test.cpp -lgmpxx -lgmp</span>
<span id="LC2" class="line" lang="plaintext">ldalessa@portland:~/temp$ ./test</span>
<span id="LC3" class="line" lang="plaintext">[portland:74170] *** Process received signal ***</span>
<span id="LC4" class="line" lang="plaintext">[portland:74170] Signal: Segmentation fault (11)</span>
<span id="LC5" class="line" lang="plaintext">[portland:74170] Signal code: Address not mapped (1)</span>
<span id="LC6" class="line" lang="plaintext">[portland:74170] Failing at address: 0x7fab9d15d0e0</span>
<span id="LC7" class="line" lang="plaintext">Segmentation fault</span></code></pre>
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<h2 dir="auto" style="font-size: 1.5em; font-weight: 600; padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-color: #eaeaea; border-bottom-style: solid; color: #303030; margin: 24px 0 16px;" align="initial">
<a id="user-content-expected-results" class="anchor" href="#expected-results" aria-hidden="true" style="color: #1068bf; margin-top: 0; float: left; margin-left: -20px; text-decoration: none; outline: none;"></a>Expected results:</h2>
<p dir="auto" style="color: #303030; margin: 0;" align="initial">No SEGFAULT.</p>
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