Description: Fix 'eval injection".
 CVE-2021-22204: Improper neutralization of user data in the DjVu file
 format in ExifTool versions 7.44 and up allows arbitrary code execution
 when parsing the malicious image
Origin: upstream release 12.24
Bug-Debian: https://bugs.debian.org/987505
Bug-Ubuntu: https://bugs.launchpad.net/bugs/1925985
Author: Phil Harvey <philharvey66@gmail.com>
Reviewed-by: gregor herrmann <gregoa@debian.org>
Last-Update: 2021-04-24
Applied-Upstream: https://github.com/exiftool/exiftool/commit/cf0f4e7dcd024ca99615bfd1102a841a25dde031#diff-fa0d652d10dbcd246e6b1df16c1e992931d3bb717a7e36157596b76bdadb3800

--- a/lib/Image/ExifTool/DjVu.pm
+++ b/lib/Image/ExifTool/DjVu.pm
@@ -227,10 +227,11 @@
                 last unless $tok =~ /(\\+)$/ and length($1) & 0x01;
                 $tok .= '"';    # quote is part of the string
             }
-            # must protect unescaped "$" and "@" symbols, and "\" at end of string
-            $tok =~ s{\\(.)|([\$\@]|\\$)}{'\\'.($2 || $1)}sge;
-            # convert C escape sequences (allowed in quoted text)
-            $tok = eval qq{"$tok"};
+            # convert C escape sequences, allowed in quoted text
+            # (note: this only converts a few of them!)
+            my %esc = ( a => "\a", b => "\b", f => "\f", n => "\n",
+                        r => "\r", t => "\t", '"' => '"', '\\' => '\\' );
+            $tok =~ s/\\(.)/$esc{$1}||'\\'.$1/egs;
         } else {                # key name
             pos($$dataPt) = pos($$dataPt) - 1;
             # allow anything in key but whitespace, braces and double quotes