From d23726d0d3d30ce451c6eadda41a2df5446ead27 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20P=C3=ADsa=C5=99?= <ppisar@redhat.com>
Date: Fri, 8 Jun 2018 09:53:16 +0200
Subject: [PATCH] Remove existing files before overwriting them
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Archive should extract only the latest same-named entry.
Extracted regular file should not be writtent into existing block
device (or any other one).

https://rt.cpan.org/Ticket/Display.html?id=125523
Signed-off-by: Petr Písař <ppisar@redhat.com>
---
 cpan/Archive-Tar/lib/Archive/Tar.pm | 14 ++++++++++++++
 1 file changed, 14 insertions(+)


diff --git a/cpan/Archive-Tar/lib/Archive/Tar.pm b/cpan/Archive-Tar/lib/Archive/Tar.pm
--- a/cpan/Archive-Tar/lib/Archive/Tar.pm
+++ b/cpan/Archive-Tar/lib/Archive/Tar.pm
@@ -845,6 +845,20 @@ sub _extract_file {
         return;
     }

+    ### If a file system already contains a block device with the same name as
+    ### the being extracted regular file, we would write the file's content
+    ### to the block device. So remove the existing file (block device) now.
+    ### If an archive contains multiple same-named entries, the last one
+    ### should replace the previous ones. So remove the old file now.
+    ### If the old entry is a symlink to a file outside of the CWD, the new
+    ### entry would create a file there. This is CVE-2018-12015
+    ### <https://rt.cpan.org/Ticket/Display.html?id=125523>.
+    if (-l $full || -e _) {
+       if (!unlink $full) {
+           $self->_error( qq[Could not remove old file '$full': $!] );
+           return;
+       }
+    }
     if( length $entry->type && $entry->is_file ) {
         my $fh = IO::File->new;
         $fh->open( '>' . $full ) or (
-- 
2.14.4