Fix CVE-2020-10595:

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-10595

Patch copied from upstream advisory:

https://seclists.org/oss-sec/2020/q1/128

diff --git a/prompting.c b/prompting.c
index e985d95..d81054f 100644
--- a/prompting.c
+++ b/prompting.c
@@ -314,26 +314,27 @@ pamk5_prompter_krb5(krb5_context context UNUSED, void *data, const char *name,
     /*
      * Reuse pam_prompts as a starting index and copy the data into the reply
      * area of the krb5_prompt structs.
      */
     pam_prompts = 0;
     if (name != NULL && !args->silent)
         pam_prompts++;
     if (banner != NULL && !args->silent)
         pam_prompts++;
     for (i = 0; i < num_prompts; i++, pam_prompts++) {
-        size_t len;
+        size_t len, allowed;

         if (resp[pam_prompts].resp == NULL)
             goto cleanup;
         len = strlen(resp[pam_prompts].resp);
-        if (len > prompts[i].reply->length)
+        allowed = prompts[i].reply->length;
+        if (allowed == 0 || len > allowed - 1)
             goto cleanup;

         /*
          * The trailing nul is not included in length, but other applications
          * expect it to be there.  Therefore, we copy one more byte than the
          * actual length of the password, but set length to just the length of
          * the password.
          */
         memcpy(prompts[i].reply->data, resp[pam_prompts].resp, len + 1);
         prompts[i].reply->length = (unsigned int) len;
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<div class='path'>path: <a href='/guix/log/?id=c6dde8b085002e68eebd09fb0f24baa86f1fa030'>root</a>/<a href='/guix/log/nix?id=c6dde8b085002e68eebd09fb0f24baa86f1fa030'>nix</a>/<a href='/guix/log/nix/libstore?id=c6dde8b085002e68eebd09fb0f24baa86f1fa030'>libstore</a>/<a href='/guix/log/nix/libstore/store-api.cc?id=c6dde8b085002e68eebd09fb0f24baa86f1fa030'>store-api.cc</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/nix/libstore/store-api.cc?id=c6dde8b085002e68eebd09fb0f24baa86f1fa030&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-09-11 16:43:30 +0200'>2022-09-11</span></td><td><a href='/guix/commit/nix/libstore/store-api.cc?id=93032586df6b925e1ed9102dc3a77aa626aa60d3'>daemon: Remove unused function exportPaths.</a><span class='msg-avail'>...<span class='msg-tooltip'>* nix/libstore/store-api.cc (exportPaths): Remove it.
* nix/libstore/store-api.hh (exportPaths): Likewise.

Signed-off-by: Mathieu Othacehe &lt;othacehe@gnu.org&gt;
</span></span></td><td>Maxime Devos</td></tr>
<tr><td><span title='2022-09-11 16:43:30 +0200'>2022-09-11</span></td><td><a href='/guix/commit/nix/libstore/store-api.cc?id=1c5f5d6d8cb3bd42ed436e31366a328598165734'>daemon: Remove unused function openStore.</a><span class='msg-avail'>...<span class='msg-tooltip'>* nix/libstore/store-api.cc (openStore): Remove it.
* nix/libstore/store-api.hh (openStore): Likewise.

Signed-off-by: Mathieu Othacehe &lt;othacehe@gnu.org&gt;
</span></span></td><td>Maxime Devos</td></tr>