On 2026-06-19 18:01, Collin Funk wrote:
FWIW, I am not able to reproduce on Fedora 44
Fedora 44 has rpm 6.0.1, and my guess is that Antonio is running an
older rpm whose rpm2archive generates nonconforming tarballs that
bleeding-edge GNU Tar rejected for security reasons.
GNU Tar doesn't need to be *that* paranoid. I installed the attached
patch on Savannah. Antonio, could you please give it a try?
Also, if my guess is right you might consider filing a bug report saying
your platform should either update to a more recent rpm version, or at
least patch rpm2archive so that it doesn't generate tarballs containing
hard links with nonzero size fields, something that POSIX prohibits.From 67981bbb1587803bb1e029393d2228492cef8c4f Mon Sep 17 00:00:00 2001
From: Paul Eggert <[email protected]>
Date: Sat, 20 Jun 2026 00:28:17 -0700
Subject: [PATCH] tar: ignore nonzero sizes in hard links etc
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Problem reported by Antonio Teixeira.
* src/list.c (read_header): When POSIX says a size field must
be zero or does not represent a data count, treat it as zero.
* tests/extrac32.at: Update to match new behavior.
We now treat hard link sizes as zero even when the size fields are
nonzero, and this means the “injected” file is treated as valid
regardless of whether we list or extract.
* tests/extrac34.at: New test.
* tests/Makefile.am (TESTSUITE_AT), tests/testsuite.at: Add it.
---
NEWS | 7 ++++++-
THANKS | 1 +
src/list.c | 16 ++++++++++++++++
tests/Makefile.am | 1 +
tests/extrac32.at | 2 ++
tests/extrac34.at | 40 ++++++++++++++++++++++++++++++++++++++++
tests/testsuite.at | 1 +
7 files changed, 67 insertions(+), 1 deletion(-)
create mode 100644 tests/extrac34.at
diff --git a/NEWS b/NEWS
index 501cfee3..8e18040d 100644
--- a/NEWS
+++ b/NEWS
@@ -1,4 +1,4 @@
-GNU tar NEWS - User visible changes. 2026-04-04
+GNU tar NEWS - User visible changes. 2026-06-20
Please send GNU tar bug reports to <[email protected]>
version 1.35.90 (git)
@@ -73,6 +73,11 @@ option.
** tar --ignore-failed-read no longer complains about a file removed
before reading.
+** tar no longer behaves erratically when reading nonzero size fields
+ in archive headers representing special files, fifos, and symlinks.
+ Although these size fields are typically zero, POSIX allows some to
+ be nonzero, and in practice they do not count data blocks.
+
* Performance improvements
** Sparse files are now read and written with larger blocksizes.
diff --git a/THANKS b/THANKS
index 8c5c99d9..fcf35695 100644
--- a/THANKS
+++ b/THANKS
@@ -39,6 +39,7 @@ Andrey A. Chernov [email protected]
Andy Gay [email protected]
Anthony G. Basile [email protected]
Antonio Jose Coutinho [email protected]
+Antonio Teixeira [email protected]
Ariel Faigon [email protected]
Arne Wichmann [email protected]
Arnold Robbins [email protected]
diff --git a/src/list.c b/src/list.c
index 5ab6de42..1c992cf4 100644
--- a/src/list.c
+++ b/src/list.c
@@ -535,6 +535,22 @@ read_header (union block **return_block, struct tar_stat_info *info,
struct posix_header const *h = &header->header;
char namebuf[sizeof h->prefix + 1 + NAME_FIELD_SIZE + 1];
+ switch (h->typeflag)
+ {
+ /* For these file types, although POSIX does not specify the
+ meaning of the size, it does say there should be no data,
+ so treat the size as zero. */
+ case BLKTYPE: case CHRTYPE: case FIFOTYPE:
+
+ /* For these file types, POSIX requires that the size be zero.
+ Be generous and accept any size as zero, as some
+ nonconforming programs generate nonzero size fields along
+ with no data. */
+ case LNKTYPE: case SYMTYPE:
+
+ info->stat.st_size = 0;
+ }
+
free (recent_long_name);
if (next_long_name)
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 103c6de7..4f666b09 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -143,6 +143,7 @@ TESTSUITE_AT = \
extrac31.at\
extrac32.at\
extrac33.at\
+ extrac34.at\
filerem01.at\
filerem02.at\
filerem03.at\
diff --git a/tests/extrac32.at b/tests/extrac32.at
index d3505fdb..af40916d 100644
--- a/tests/extrac32.at
+++ b/tests/extrac32.at
@@ -36,11 +36,13 @@ base64 -d < archive.in | xz -c -d > archive.tar
AT_CHECK([tar tf archive.tar],
[0],
[carrier_entry
+injected.txt
marker.txt
])
AT_CHECK([tar xvf archive.tar],
[0],
[carrier_entry
+injected.txt
marker.txt
])
AT_CLEANUP
diff --git a/tests/extrac34.at b/tests/extrac34.at
new file mode 100644
index 00000000..1cedb463
--- /dev/null
+++ b/tests/extrac34.at
@@ -0,0 +1,40 @@
+# Check hard link with nonzero size field in tarball. -*- Autotest -*-
+
+# Copyright 2026 Free Software Foundation, Inc.
+
+# This file is part of GNU tar.
+
+# GNU tar is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+
+# GNU tar is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+# Check extracting from a nonconforming tarball that has
+# a hard link with nonzero size.
+
+AT_SETUP([hard link with a nonzero size field])
+AT_KEYWORDS([extract extrac34 hard link])
+AT_DATA([archive.in],
+[/Td6WFoAAATm1rRGBMBwgFAhARwAAAAAAAAAAAbKrCjgJ/8AaF0AMIAzUBhoiawFdYeRen4lxlj0
+QWRLpUM+28ArRsXVY5bGv4H5kijsqiJ4Z9YIVhZd01+IppF+AkltS60aB8fuUW35Tp/3XzUx9Mq2
+4ypJFzvcgHXsSIvc9L+mmTDuHzhvJQ/oe7ya8QAASbOfD7CgZcIAAYwBgFAAAEWxohaxxGf7AgAA
+AAAEWVo=
+])
+AT_CHECK([base64 --help >/dev/null 2>&1 || AT_SKIP_TEST
+xz --help >/dev/null 2>&1 || AT_SKIP_TEST
+base64 -d < archive.in | xz -c -d > archive.tar
+])
+AT_CHECK([mkdir dir
+])
+AT_CHECK([tar -C dir -xf archive.tar || exit 1
+cmp dir/a dir/b
+])
+AT_CLEANUP
diff --git a/tests/testsuite.at b/tests/testsuite.at
index 70d36a5a..ab30c2ab 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -360,6 +360,7 @@ m4_include([extrac30.at])
m4_include([extrac31.at])
m4_include([extrac32.at])
m4_include([extrac33.at])
+m4_include([extrac34.at])
m4_include([backup01.at])
--
2.53.0
