From 08e3451d7b3b714ad63a27f1b9c2a23ee75d15ee Mon Sep 17 00:00:00 2001

From: Father Chrysostomos <[email protected]>

Date: Sat, 2 Jul 2016 22:56:51 -0700

Subject: [PATCH] =?utf8?q?Don=E2=80=99t=20let=20XSLoader=20load=20relative?=

 =?utf8?q?=20paths?=

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[rt.cpan.org #115808]

The logic in XSLoader for determining the library goes like this:

    my $c = () = split(/::/,$caller,-1);

    $modlibname =~ s,[\\/][^\\/]+$,, while $c--;    # Q&D basename

    my $file = "$modlibname/auto/$modpname/$modfname.bundle";

(That last line varies by platform.)

$caller is the calling package.  $modlibname is the calling file.  It

removes as many path segments from $modlibname as there are segments

in $caller.  So if you have Foo/Bar/XS.pm calling XSLoader from the

Foo::Bar package, the $modlibname will end up containing the path in

@INC where XS.pm was found, followed by "/Foo".  Usually the fallback

to Dynaloader::bootstrap_inherit, which does an @INC search, makes

things Just Work.

But if our hypothetical Foo/Bar/XS.pm actually calls

XSLoader::load from inside a string eval, then path ends up being

"(eval 1)/auto/Foo/Bar/Bar.bundle".

So if someone creates a directory named ‘(eval 1)’ with a naughty

binary file in it, it will be loaded if a script using Foo::Bar is run

in the parent directory.

This commit makes XSLoader fall back to Dynaloader’s @INC search if

the calling file has a relative path that is not found in @INC.

---

 dist/XSLoader/XSLoader_pm.PL | 25 +++++++++++++++++++++++++

 dist/XSLoader/t/XSLoader.t   | 27 ++++++++++++++++++++++++++-

 2 files changed, 51 insertions(+), 1 deletion(-)

--- perl-5.12.5/dist/XSLoader/XSLoader_pm.PL.old

+++ perl-5.12.5/dist/XSLoader/XSLoader_pm.PL

@@ -74,6 +74,31 @@

     my $modlibname = (caller())[1];

     my $c = @modparts;

     $modlibname =~ s,[\\/][^\\/]+$,, while $c--;	# Q&D basename

+    # Does this look like a relative path?

+    if ($modlibname !~ m|^[\\/]|) {

+        # Someone may have a #line directive that changes the file name, or

+        # may be calling XSLoader::load from inside a string eval.  We cer-

+        # tainly do not want to go loading some code that is not in @INC,

+        # as it could be untrusted.

+        #

+        # We could just fall back to DynaLoader here, but then the rest of

+        # this function would go untested in the perl core, since all @INC

+        # paths are relative during testing.  That would be a time bomb

+        # waiting to happen, since bugs could be introduced into the code.

+        #

+        # So look through @INC to see if $modlibname is in it.  A rela-

+        # tive $modlibname is not a common occurrence, so this block is

+        # not hot code.

+        FOUND: {

+            for (@INC) {

+                if ($_ eq $modlibname) {

+                    last FOUND;

+                }

+            }

+            # Not found.  Fall back to DynaLoader.

+            goto \&XSLoader::bootstrap_inherit;

+        }

+    }

     my $file = "$modlibname/auto/$modpname/$modfname.$dl_dlext";

 #   print STDERR "XSLoader::load for $module ($file)\n" if $dl_debug;

--- perl-5.12.5/dist/XSLoader/t/XSLoader.t.old

+++ perl-5.12.5/dist/XSLoader/t/XSLoader.t

@@ -30,7 +30,7 @@

     'Time::HiRes'=> q| ::can_ok( 'Time::HiRes' => 'usleep'  ) |,  # 5.7.3

 );

-plan tests => keys(%modules) * 3 + 5;

+plan tests => keys(%modules) * 3 + 6;

 # Try to load the module

 use_ok( 'XSLoader' );

@@ -76,3 +76,27 @@

     }

 }

+SKIP: {

+  skip "File::Path not available", 1

+    unless eval { require File::Path };

+  my $name = "phooo$$";

+  File::Path::make_path("$name/auto/Foo/Bar");

+  open my $fh,

+    ">$name/auto/Foo/Bar/Bar.$Config::Config{'dlext'}";

+  close $fh;

+  my $fell_back;

+  local *XSLoader::bootstrap_inherit = sub {

+    $fell_back++;

+    # Break out of the calling subs

+    goto the_test;

+  };

+  eval <<END;

+#line 1 $name

+package Foo::Bar;

+XSLoader::load("Foo::Bar");

+END

+ the_test:

+  ok $fell_back,

+    'XSLoader will not load relative paths based on (caller)[1]';

+  File::Path::remove_tree($name);

+}