Fix CVE-2017-17969:

https://sourceforge.net/p/p7zip/bugs/204/
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-17969

Patch copied from Debian.

Subject: Heap-based buffer overflow in 7zip/Compress/ShrinkDecoder.cpp
Origin: vendor, https://sourceforge.net/p/p7zip/bugs/_discuss/thread/0920f369/27d7/attachment/CVE-2017-17969.patch
Forwarded: https://sourceforge.net/p/p7zip/bugs/_discuss/thread/0920f369/#27d7
Bug: https://sourceforge.net/p/p7zip/bugs/204/
Bug-Debian: https://bugs.debian.org/888297
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-17969
Author: Antoine Beaupré <anarcat@debian.org>
Reviewed-by: Salvatore Bonaccorso <carnil@debian.org>
Last-Update: 2018-02-01
Applied-Upstream: 18.00-beta

--- a/CPP/7zip/Compress/ShrinkDecoder.cpp
+++ b/CPP/7zip/Compress/ShrinkDecoder.cpp
@@ -121,8 +121,13 @@ HRESULT CDecoder::CodeReal(ISequentialIn
     {
       _stack[i++] = _suffixes[cur];
       cur = _parents[cur];
+      if (cur >= kNumItems || i >= kNumItems)
+        break;
     }
-    
+
+    if (cur >= kNumItems || i >= kNumItems)
+      break;
+
     _stack[i++] = (Byte)cur;
     lastChar2 = (Byte)cur;
 
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<tr><td><span title='2024-07-10 15:53:54 +0200'>2024-07-10</span></td><td><a href='/guix/commit/gnu/packages/gnucash.scm?id=45cfc7a8f359e167ccf020d8a089d8a9b7606042'>gnu: gnucash: Update to 5.8.</a><span class='msg-avail'>...</span></td><td>gemmaro</td></tr>
<tr><td><span title='2024-05-04 19:14:27 +0200'>2024-05-04</span></td><td><a href='/guix/commit/gnu/packages/gnucash.scm?id=dde37247fa9d56b26b8967bb4d70a7598ab2c330'>gnu: gnucash: Update to 5.6.</a><span class='msg-avail'>...</span></td><td>Steve George</td></tr>
<tr><td><span title='2024-05-04 19:14:25 +0200'>2024-05-04</span></td><td><a href='/guix/commit/gnu/packages/gnucash.scm?id=3ca4d48322f6ac7fa503fcb0b1ed15db8e9fc990'>gnu: aqbanking: Update to 6.5.4.</a><span class='msg-avail'>...</span></td><td>Steve George</td></tr>
<tr><td><span title='2024-05-04 19:14:25 +0200'>2024-05-04</span></td><td><a href='/guix/commit/gnu/packages/gnucash.scm?id=96a0a7431ff216d1a3c8ca7858e150e557aebe4d'>gnu: gwenhywfar: Update to 5.10.2.</a><span class='msg-avail'>...</span></td><td>Steve George</td></tr>
<tr><td><span title='2024-04-23 14:31:58 +0100'>2024-04-23</span></td><td><a href='/guix/commit/gnu/packages/gnucash.scm?id=6f50fc7dbc1e68415fd5c7ba384c71c60a6c92ec'>gnu: gnucash: Update to 5.6.</a><span class='msg-avail'>...</span></td><td>Andy Tai</td></tr>
<tr><td><span title='2024-02-28 09:50:42 +0200'>2024-02-28</span></td><td><a href='/guix/commit/gnu/packages/gnucash.scm?id=7947d47c9b891d2461ca9e7c53048d0e44294b5d'>gnu: gnucash: Update to 5.5.</a><span class='msg-avail'>...</span></td><td>Efraim Flashner</td></tr>