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528b4afb42
perl/perl-5.42.0-CVE-2025-40909-Clone-dirhandles-without-fchdir.patch
Jitka Plesnikova 528b4afb42 Resolves: RHEL-102564 
Fix CVE-2025-40909 - Clone dirhandles without fchdir
2025-07-10 09:27:30 +02:00

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From 918bfff86ca8d6d4e4ec5b30994451e0bd74aba9 Mon Sep 17 00:00:00 2001
From: Leon Timmermans <fawaka@gmail.com>
Date: Fri, 23 May 2025 15:40:41 +0200
Subject: [PATCH] CVE-2025-40909: Clone dirhandles without fchdir
This uses fdopendir and dup to dirhandles. This means it won't change
working directory during thread cloning, which prevents race conditions
that can happen if a third thread is active at the same time.
---
Configure | 6 ++
Cross/config.sh-arm-linux | 1 +
Cross/config.sh-arm-linux-n770 | 1 +
Porting/Glossary | 5 ++
Porting/config.sh | 1 +
config_h.SH | 6 ++
configure.com | 1 +
plan9/config_sh.sample | 1 +
sv.c | 91 +----------------------------
t/op/threads-dirh.t | 104 +--------------------------------
win32/config.gc | 1 +
win32/config.vc | 1 +
12 files changed, 28 insertions(+), 191 deletions(-)
diff --git a/Configure b/Configure
index 44c12ced4014..7a13249caa96 100755
--- a/Configure
+++ b/Configure
@@ -478,6 +478,7 @@ d_fd_set=''
d_fds_bits=''
d_fdclose=''
d_fdim=''
+d_fdopendir=''
d_fegetround=''
d_ffs=''
d_ffsl=''
@@ -13344,6 +13345,10 @@ esac
set i_fcntl
eval $setvar
+: see if fdopendir exists
+set fdopendir d_fdopendir
+eval $inlibc
+
: see if fork exists
set fork d_fork
eval $inlibc
@@ -25052,6 +25057,7 @@ d_flockproto='$d_flockproto'
d_fma='$d_fma'
d_fmax='$d_fmax'
d_fmin='$d_fmin'
+d_fdopendir='$d_fdopendir'
d_fork='$d_fork'
d_fp_class='$d_fp_class'
d_fp_classify='$d_fp_classify'
diff --git a/Cross/config.sh-arm-linux b/Cross/config.sh-arm-linux
index bfa0b00d5f0f..9e056539198b 100644
--- a/Cross/config.sh-arm-linux
+++ b/Cross/config.sh-arm-linux
@@ -212,6 +212,7 @@ d_fd_macros='define'
d_fd_set='define'
d_fdclose='undef'
d_fdim='undef'
+d_fdopendir=undef
d_fds_bits='undef'
d_fegetround='define'
d_ffs='undef'
diff --git a/Cross/config.sh-arm-linux-n770 b/Cross/config.sh-arm-linux-n770
index 47ad5c37e3fd..365e4c4f9671 100644
--- a/Cross/config.sh-arm-linux-n770
+++ b/Cross/config.sh-arm-linux-n770
@@ -211,6 +211,7 @@ d_fd_macros='define'
d_fd_set='define'
d_fdclose='undef'
d_fdim='undef'
+d_fdopendir=undef
d_fds_bits='undef'
d_fegetround='define'
d_ffs='undef'
diff --git a/Porting/Glossary b/Porting/Glossary
index bb505c653b0b..8b2965ca99c6 100644
--- a/Porting/Glossary
+++ b/Porting/Glossary
@@ -947,6 +947,11 @@ d_fmin (d_fmin.U):
This variable conditionally defines the HAS_FMIN symbol, which
indicates to the C program that the fmin() routine is available.
+d_fdopendir (d_fdopendir.U):
+ This variable conditionally defines the HAS_FORK symbol, which
+ indicates that the fdopen routine is available to open a
+ directory descriptor.
+
d_fork (d_fork.U):
This variable conditionally defines the HAS_FORK symbol, which
indicates to the C program that the fork() routine is available.
diff --git a/Porting/config.sh b/Porting/config.sh
index a921f7e1c79a..6231ea0f31ea 100644
--- a/Porting/config.sh
+++ b/Porting/config.sh
@@ -223,6 +223,7 @@ d_fd_macros='define'
d_fd_set='define'
d_fdclose='undef'
d_fdim='define'
+d_fdopendir='define'
d_fds_bits='define'
d_fegetround='define'
d_ffs='define'
diff --git a/config_h.SH b/config_h.SH
index da0f2dbcd7b7..5a0f81cf2011 100755
--- a/config_h.SH
+++ b/config_h.SH
@@ -142,6 +142,12 @@ sed <<!GROK!THIS! >$CONFIG_H -e 's!^#undef\(.*/\)\*!/\*#define\1 \*!' -e 's!^#un
*/
#$d_fcntl HAS_FCNTL /**/
+/* HAS_FDOPENDIR:
+ * This symbol, if defined, indicates that the fdopen routine is
+ * available to open a directory descriptor.
+ */
+#$d_fdopendir HAS_FDOPENDIR /**/
+
/* HAS_FGETPOS:
* This symbol, if defined, indicates that the fgetpos routine is
* available to get the file position indicator, similar to ftell().
diff --git a/configure.com b/configure.com
index 99527c180bfc..7c38711bb85d 100644
--- a/configure.com
+++ b/configure.com
@@ -6010,6 +6010,7 @@ $ WC "d_fd_set='" + d_fd_set + "'"
$ WC "d_fd_macros='define'"
$ WC "d_fdclose='undef'"
$ WC "d_fdim='" + d_fdim + "'"
+$ WC "d_fdopendir='undef'"
$ WC "d_fds_bits='define'"
$ WC "d_fegetround='undef'"
$ WC "d_ffs='undef'"
diff --git a/plan9/config_sh.sample b/plan9/config_sh.sample
index 636acbdf6db3..246bad954424 100644
--- a/plan9/config_sh.sample
+++ b/plan9/config_sh.sample
@@ -212,6 +212,7 @@ d_fd_macros='undef'
d_fd_set='undef'
d_fdclose='undef'
d_fdim='undef'
+d_fdopendir=undef
d_fds_bits='undef'
d_fegetround='undef'
d_ffs='undef'
diff --git a/sv.c b/sv.c
index ae6d09dea28a..8a005b2d165b 100644
--- a/sv.c
+++ b/sv.c
@@ -14096,15 +14096,6 @@ Perl_dirp_dup(pTHX_ DIR *const dp, CLONE_PARAMS *const param)
{
DIR *ret;
-#if defined(HAS_FCHDIR) && defined(HAS_TELLDIR) && defined(HAS_SEEKDIR)
- DIR *pwd;
- const Direntry_t *dirent;
- char smallbuf[256]; /* XXX MAXPATHLEN, surely? */
- char *name = NULL;
- STRLEN len = 0;
- long pos;
-#endif
-
PERL_UNUSED_CONTEXT;
PERL_ARGS_ASSERT_DIRP_DUP;
@@ -14116,89 +14107,13 @@ Perl_dirp_dup(pTHX_ DIR *const dp, CLONE_PARAMS *const param)
if (ret)
return ret;
-#if defined(HAS_FCHDIR) && defined(HAS_TELLDIR) && defined(HAS_SEEKDIR)
+#ifdef HAS_FDOPENDIR
PERL_UNUSED_ARG(param);
- /* create anew */
-
- /* open the current directory (so we can switch back) */
- if (!(pwd = PerlDir_open("."))) return (DIR *)NULL;
-
- /* chdir to our dir handle and open the present working directory */
- if (fchdir(my_dirfd(dp)) < 0 || !(ret = PerlDir_open("."))) {
- PerlDir_close(pwd);
- return (DIR *)NULL;
- }
- /* Now we should have two dir handles pointing to the same dir. */
-
- /* Be nice to the calling code and chdir back to where we were. */
- /* XXX If this fails, then what? */
- PERL_UNUSED_RESULT(fchdir(my_dirfd(pwd)));
+ ret = fdopendir(dup(my_dirfd(dp)));
- /* We have no need of the pwd handle any more. */
- PerlDir_close(pwd);
-
-#ifdef DIRNAMLEN
-# define d_namlen(d) (d)->d_namlen
-#else
-# define d_namlen(d) strlen((d)->d_name)
-#endif
- /* Iterate once through dp, to get the file name at the current posi-
- tion. Then step back. */
- pos = PerlDir_tell(dp);
- if ((dirent = PerlDir_read(dp))) {
- len = d_namlen(dirent);
- if (len > sizeof(dirent->d_name) && sizeof(dirent->d_name) > PTRSIZE) {
- /* If the len is somehow magically longer than the
- * maximum length of the directory entry, even though
- * we could fit it in a buffer, we could not copy it
- * from the dirent. Bail out. */
- PerlDir_close(ret);
- return (DIR*)NULL;
- }
- if (len <= sizeof smallbuf) name = smallbuf;
- else Newx(name, len, char);
- Move(dirent->d_name, name, len, char);
- }
- PerlDir_seek(dp, pos);
-
- /* Iterate through the new dir handle, till we find a file with the
- right name. */
- if (!dirent) /* just before the end */
- for(;;) {
- pos = PerlDir_tell(ret);
- if (PerlDir_read(ret)) continue; /* not there yet */
- PerlDir_seek(ret, pos); /* step back */
- break;
- }
- else {
- const long pos0 = PerlDir_tell(ret);
- for(;;) {
- pos = PerlDir_tell(ret);
- if ((dirent = PerlDir_read(ret))) {
- if (len == (STRLEN)d_namlen(dirent)
- && memEQ(name, dirent->d_name, len)) {
- /* found it */
- PerlDir_seek(ret, pos); /* step back */
- break;
- }
- /* else we are not there yet; keep iterating */
- }
- else { /* This is not meant to happen. The best we can do is
- reset the iterator to the beginning. */
- PerlDir_seek(ret, pos0);
- break;
- }
- }
- }
-#undef d_namlen
-
- if (name && name != smallbuf)
- Safefree(name);
-#endif
-
-#ifdef WIN32
+#elif defined(WIN32)
ret = win32_dirp_dup(dp, param);
#endif
diff --git a/t/op/threads-dirh.t b/t/op/threads-dirh.t
index bb4bcfc14184..14c399ca19cd 100644
--- a/t/op/threads-dirh.t
+++ b/t/op/threads-dirh.t
@@ -13,16 +13,12 @@ BEGIN {
skip_all_if_miniperl("no dynamic loading on miniperl, no threads");
skip_all("runs out of memory on some EBCDIC") if $ENV{PERL_SKIP_BIG_MEM_TESTS};
- plan(6);
+ plan(1);
}
use strict;
use warnings;
use threads;
-use threads::shared;
-use File::Path;
-use File::Spec::Functions qw 'updir catdir';
-use Cwd 'getcwd';
# Basic sanity check: make sure this does not crash
fresh_perl_is <<'# this is no comment', 'ok', {}, 'crash when duping dirh';
@@ -31,101 +27,3 @@ fresh_perl_is <<'# this is no comment', 'ok', {}, 'crash when duping dirh';
async{}->join for 1..2;
print "ok";
# this is no comment
-
-my $dir;
-SKIP: {
- skip "telldir or seekdir not defined on this platform", 5
- if !$Config::Config{d_telldir} || !$Config::Config{d_seekdir};
- my $skip = sub {
- chdir($dir);
- chdir updir;
- skip $_[0], 5
- };
-
- if(!$Config::Config{d_fchdir} && $^O ne "MSWin32") {
- $::TODO = 'dir handle cloning currently requires fchdir on non-Windows platforms';
- }
-
- my @w :shared; # warnings accumulator
- local $SIG{__WARN__} = sub { push @w, $_[0] };
-
- $dir = catdir getcwd(), "thrext$$" . int rand() * 100000;
-
- rmtree($dir) if -d $dir;
- mkdir($dir);
-
- # Create a dir structure like this:
- # $dir
- # |
- # `- toberead
- # |
- # +---- thrit
- # |
- # +---- rile
- # |
- # `---- zor
-
- chdir($dir);
- mkdir 'toberead';
- chdir 'toberead';
- {open my $fh, ">thrit" or &$skip("Cannot create file thrit")}
- {open my $fh, ">rile" or &$skip("Cannot create file rile")}
- {open my $fh, ">zor" or &$skip("Cannot create file zor")}
- chdir updir;
-
- # Then test that dir iterators are cloned correctly.
-
- opendir my $toberead, 'toberead';
- my $start_pos = telldir $toberead;
- my @first_2 = (scalar readdir $toberead, scalar readdir $toberead);
- my @from_thread = @{; async { [readdir $toberead ] } ->join };
- my @from_main = readdir $toberead;
- is join('-', sort @from_thread), join('-', sort @from_main),
- 'dir iterator is copied from one thread to another';
- like
- join('-', "", sort(@first_2, @from_thread), ""),
- qr/(?<!-rile)-rile-thrit-zor-(?!zor-)/i,
- 'cloned iterator iterates exactly once over everything not already seen';
-
- seekdir $toberead, $start_pos;
- readdir $toberead for 1 .. @first_2+@from_thread;
- {
- local $::TODO; # This always passes when dir handles are not cloned.
- is
- async { readdir $toberead // 'undef' } ->join, 'undef',
- 'cloned dir iterator that points to the end of the directory'
- ;
- }
-
- # Make sure the cloning code can handle file names longer than 255 chars
- SKIP: {
- chdir 'toberead';
- open my $fh,
- ">floccipaucinihilopilification-"
- . "pneumonoultramicroscopicsilicovolcanoconiosis-"
- . "lopadotemachoselachogaleokranioleipsanodrimypotrimmatosilphiokarabo"
- . "melitokatakechymenokichlepikossyphophattoperisteralektryonoptokephal"
- . "liokinklopeleiolagoiosiraiobaphetraganopterygon"
- or
- chdir updir,
- skip("OS does not support long file names (and I mean *long*)", 1);
- chdir updir;
- opendir my $dirh, "toberead";
- my $test_name
- = "dir iterators can be cloned when the next fn > 255 chars";
- while() {
- my $pos = telldir $dirh;
- my $fn = readdir($dirh);
- if(!defined $fn) { fail($test_name); last SKIP; }
- if($fn =~ 'lagoio') {
- seekdir $dirh, $pos;
- last;
- }
- }
- is length async { scalar readdir $dirh } ->join, 258, $test_name;
- }
-
- is scalar @w, 0, 'no warnings during all that' or diag @w;
- chdir updir;
-}
-rmtree($dir);
diff --git a/win32/config.gc b/win32/config.gc
index f8776188c09c..34aa8de6ed75 100644
--- a/win32/config.gc
+++ b/win32/config.gc
@@ -199,6 +199,7 @@ d_fd_macros='define'
d_fd_set='define'
d_fdclose='undef'
d_fdim='undef'
+d_fdopendir='undef'
d_fds_bits='define'
d_fegetround='undef'
d_ffs='undef'
diff --git a/win32/config.vc b/win32/config.vc
index 619979e22b53..536085fe94e0 100644
--- a/win32/config.vc
+++ b/win32/config.vc
@@ -199,6 +199,7 @@ d_fd_macros='define'
d_fd_set='define'
d_fdclose='undef'
d_fdim='undef'
+d_fdopendir='undef'
d_fds_bits='define'
d_fegetround='undef'
d_ffs='undef'
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