gnu: libexif: Fix CVE-2018-20030.
* gnu/packages/photo.scm (libexif)[source]: Add patch. * gnu/packages/patches/libexif-CVE-2018-20030.patch: New file. * gnu/local.mk (dist_patch_DATA): Register it.master
Efraim Flashner
parent
037036cb19
commit
5a4e5c26cc
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@ -1006,6 +1006,7 @@ dist_patch_DATA = \
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%D%/packages/patches/libdrm-symbol-check.patch \
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%D%/packages/patches/libexif-CVE-2016-6328.patch \
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%D%/packages/patches/libexif-CVE-2017-7544.patch \
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%D%/packages/patches/libexif-CVE-2018-20030.patch \
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%D%/packages/patches/libgcrypt-make-yat2m-reproducible.patch \
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%D%/packages/patches/libgit2-avoid-python.patch \
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%D%/packages/patches/libgit2-mtime-0.patch \
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@ -0,0 +1,120 @@
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https://github.com/libexif/libexif/commit/6aa11df549114ebda520dde4cdaea2f9357b2c89.patch
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NEWS section was removed
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'12' -> '30' on line 79
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From 6aa11df549114ebda520dde4cdaea2f9357b2c89 Mon Sep 17 00:00:00 2001
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From: Dan Fandrich <dan@coneharvesters.com>
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Date: Fri, 12 Oct 2018 16:01:45 +0200
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Subject: [PATCH] Improve deep recursion detection in
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exif_data_load_data_content.
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The existing detection was still vulnerable to pathological cases
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causing DoS by wasting CPU. The new algorithm takes the number of tags
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into account to make it harder to abuse by cases using shallow recursion
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but with a very large number of tags. This improves on commit 5d28011c
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which wasn't sufficient to counter this kind of case.
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The limitation in the previous fix was discovered by Laurent Delosieres,
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Secunia Research at Flexera (Secunia Advisory SA84652) and is assigned
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the identifier CVE-2018-20030.
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---
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NEWS | 1 +
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libexif/exif-data.c | 45 +++++++++++++++++++++++++++++++++++++--------
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2 files changed, 38 insertions(+), 8 deletions(-)
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diff --git a/libexif/exif-data.c b/libexif/exif-data.c
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index e35403d..a6f9c94 100644
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--- a/libexif/exif-data.c
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+++ b/libexif/exif-data.c
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@@ -35,6 +35,7 @@
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#include <libexif/olympus/exif-mnote-data-olympus.h>
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#include <libexif/pentax/exif-mnote-data-pentax.h>
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+#include <math.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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@@ -350,6 +351,20 @@ if (data->ifd[(i)]->count) { \
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break; \
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}
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+/*! Calculate the recursion cost added by one level of IFD loading.
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+ *
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+ * The work performed is related to the cost in the exponential relation
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+ * work=1.1**cost
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+ */
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+static unsigned int
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+level_cost(unsigned int n)
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+{
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+ static const double log_1_1 = 0.09531017980432493;
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+
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+ /* Adding 0.1 protects against the case where n==1 */
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+ return ceil(log(n + 0.1)/log_1_1);
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+}
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+
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/*! Load data for an IFD.
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*
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* \param[in,out] data #ExifData
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@@ -357,13 +372,13 @@ if (data->ifd[(i)]->count) { \
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* \param[in] d pointer to buffer containing raw IFD data
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* \param[in] ds size of raw data in buffer at \c d
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* \param[in] offset offset into buffer at \c d at which IFD starts
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- * \param[in] recursion_depth number of times this function has been
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- * recursively called without returning
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+ * \param[in] recursion_cost factor indicating how expensive this recursive
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+ * call could be
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*/
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static void
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exif_data_load_data_content (ExifData *data, ExifIfd ifd,
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const unsigned char *d,
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- unsigned int ds, unsigned int offset, unsigned int recursion_depth)
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+ unsigned int ds, unsigned int offset, unsigned int recursion_cost)
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{
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ExifLong o, thumbnail_offset = 0, thumbnail_length = 0;
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ExifShort n;
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@@ -378,9 +393,20 @@ exif_data_load_data_content (ExifData *data, ExifIfd ifd,
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if ((((int)ifd) < 0) || ( ((int)ifd) >= EXIF_IFD_COUNT))
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return;
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- if (recursion_depth > 30) {
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+ if (recursion_cost > 170) {
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+ /*
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+ * recursion_cost is a logarithmic-scale indicator of how expensive this
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+ * recursive call might end up being. It is an indicator of the depth of
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+ * recursion as well as the potential for worst-case future recursive
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+ * calls. Since it's difficult to tell ahead of time how often recursion
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+ * will occur, this assumes the worst by assuming every tag could end up
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+ * causing recursion.
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+ * The value of 170 was chosen to limit typical EXIF structures to a
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+ * recursive depth of about 6, but pathological ones (those with very
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+ * many tags) to only 2.
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+ */
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exif_log (data->priv->log, EXIF_LOG_CODE_CORRUPT_DATA, "ExifData",
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- "Deep recursion detected!");
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+ "Deep/expensive recursion detected!");
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return;
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}
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@@ -422,15 +448,18 @@ exif_data_load_data_content (ExifData *data, ExifIfd ifd,
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switch (tag) {
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case EXIF_TAG_EXIF_IFD_POINTER:
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CHECK_REC (EXIF_IFD_EXIF);
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- exif_data_load_data_content (data, EXIF_IFD_EXIF, d, ds, o, recursion_depth + 1);
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+ exif_data_load_data_content (data, EXIF_IFD_EXIF, d, ds, o,
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+ recursion_cost + level_cost(n));
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break;
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case EXIF_TAG_GPS_INFO_IFD_POINTER:
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CHECK_REC (EXIF_IFD_GPS);
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- exif_data_load_data_content (data, EXIF_IFD_GPS, d, ds, o, recursion_depth + 1);
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+ exif_data_load_data_content (data, EXIF_IFD_GPS, d, ds, o,
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+ recursion_cost + level_cost(n));
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break;
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case EXIF_TAG_INTEROPERABILITY_IFD_POINTER:
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CHECK_REC (EXIF_IFD_INTEROPERABILITY);
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- exif_data_load_data_content (data, EXIF_IFD_INTEROPERABILITY, d, ds, o, recursion_depth + 1);
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+ exif_data_load_data_content (data, EXIF_IFD_INTEROPERABILITY, d, ds, o,
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+ recursion_cost + level_cost(n));
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break;
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case EXIF_TAG_JPEG_INTERCHANGE_FORMAT:
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thumbnail_offset = o;
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@ -2,7 +2,7 @@
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;;; Copyright © 2014, 2015, 2017, 2019 Ludovic Courtès <ludo@gnu.org>
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;;; Copyright © 2015 Ricardo Wurmus <rekado@elephly.net>
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;;; Copyright © 2015, 2017 Andreas Enge <andreas@enge.fr>
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;;; Copyright © 2016, 2017, 2018 Efraim Flashner <efraim@flashner.co.il>
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;;; Copyright © 2016, 2017, 2018, 2019 Efraim Flashner <efraim@flashner.co.il>
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;;; Copyright © 2017 Roel Janssen <roel@gnu.org>
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;;; Copyright © 2018, 2019 Tobias Geerinckx-Rice <me@tobias.gr>
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;;; Copyright © 2018 Leo Famulari <leo@famulari.name>
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@ -117,7 +117,8 @@ cameras (CRW/CR2, NEF, RAF, DNG, and others).")
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(uri (string-append "mirror://sourceforge/libexif/libexif/"
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version "/libexif-" version ".tar.bz2"))
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(patches (search-patches "libexif-CVE-2016-6328.patch"
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"libexif-CVE-2017-7544.patch"))
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"libexif-CVE-2017-7544.patch"
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"libexif-CVE-2018-20030.patch"))
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(sha256
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(base32
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"06nlsibr3ylfwp28w8f5466l6drgrnydgxrm4jmxzrmk5svaxk8n"))))
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