user/libexif: patch for CVE-2017-7544 and CVE-2018-20030 (#143)

user/libexif/APKBUILD

 # Maintainer: 
 pkgname=libexif
 pkgver=0.6.21
-pkgrel=2
+pkgrel=3
 pkgdesc="Library to parse EXIF metadata"
 url="https://sourceforge.net/projects/libexif"
 arch="all"
@@ -9,16 +9,21 @@ license="LGPL-2.0+"
 subpackages="$pkgname-dev $pkgname-doc $pkgname-lang"
 depends=""
 makedepends=""
-source="https://downloads.sourceforge.net/$pkgname/$pkgname-$pkgver.tar.bz2"
+source="https://downloads.sourceforge.net/$pkgname/$pkgname-$pkgver.tar.bz2
+	CVE-2017-7544.patch
+	CVE-2018-20030.patch"
+
+# secfixes:
+#   0.6.21-r3:
+#     - CVE-2017-7544
+#     - CVE-2018-20030
 
 prepare() {
-	cd "$builddir"
 	update_config_sub
 	default_prepare
 }
 
 build() {
-	cd "$builddir"
 	./configure \
 		--build=$CBUILD \
 		--host=$CHOST \
@@ -27,12 +32,13 @@ build() {
 }
 
 check() {
-	cd "$builddir"
 	make check
 }
 
 package() {
-	cd "$builddir"
 	make DESTDIR="$pkgdir" install
 }
-sha512sums="4e0fe2abe85d1c95b41cb3abe1f6333dc3a9eb69dba106a674a78d74a4d5b9c5a19647118fa1cc2d72b98a29853394f1519eda9e2889eb28d3be26b21c7cfc35  libexif-0.6.21.tar.bz2"
+
+sha512sums="4e0fe2abe85d1c95b41cb3abe1f6333dc3a9eb69dba106a674a78d74a4d5b9c5a19647118fa1cc2d72b98a29853394f1519eda9e2889eb28d3be26b21c7cfc35  libexif-0.6.21.tar.bz2
+d529c6c5bd26dc21c0946702574184e1f61c2bfd4fb95b41e314f486a0dd55571963ff2cad566d2fb0804de3c0799bcd956c15a3dc10a520ce207728edad4e2d  CVE-2017-7544.patch
+0d6123bd275ace338ad9cebb31a2e714de0141b91860f07394b281686a5393566c3f4159679d4ba689ae7ea69ae2e412b158c3deb451c40c210b5817f6888bbc  CVE-2018-20030.patch"

user/libexif/CVE-2017-7544.patch

+From c39acd1692023b26290778a02a9232c873f9d71a Mon Sep 17 00:00:00 2001
+From: Marcus Meissner <marcus@jet.franken.de>
+Date: Tue, 25 Jul 2017 23:38:56 +0200
+Subject: [PATCH] On saving makernotes, make sure the makernote container tags
+ has a type with 1 byte components.
+
+Fixes (at least):
+	https://sourceforge.net/p/libexif/bugs/130
+	https://sourceforge.net/p/libexif/bugs/129
+---
+ libexif/exif-data.c | 6 ++++++
+ 1 file changed, 6 insertions(+)
+
+diff --git a/libexif/exif-data.c b/libexif/exif-data.c
+index 67df4db..91f4c33 100644
+--- a/libexif/exif-data.c
++++ b/libexif/exif-data.c
+@@ -255,6 +255,12 @@ exif_data_save_data_entry (ExifData *data, ExifEntry *e,
+ 			exif_mnote_data_set_offset (data->priv->md, *ds - 6);
+ 			exif_mnote_data_save (data->priv->md, &e->data, &e->size);
+ 			e->components = e->size;
++			if (exif_format_get_size (e->format) != 1) {
++				/* e->format is taken from input code,
++				 * but we need to make sure it is a 1 byte
++				 * entity due to the multiplication below. */
++				e->format = EXIF_FORMAT_UNDEFINED;
++			}
+ 		}
+ 	}
+ 

user/libexif/CVE-2018-20030.patch

+Edited slightly to backport to stable
+
+From 6aa11df549114ebda520dde4cdaea2f9357b2c89 Mon Sep 17 00:00:00 2001
+From: Dan Fandrich <dan@coneharvesters.com>
+Date: Fri, 12 Oct 2018 16:01:45 +0200
+Subject: [PATCH] Improve deep recursion detection in
+ exif_data_load_data_content.
+
+The existing detection was still vulnerable to pathological cases
+causing DoS by wasting CPU. The new algorithm takes the number of tags
+into account to make it harder to abuse by cases using shallow recursion
+but with a very large number of tags.  This improves on commit 5d28011c
+which wasn't sufficient to counter this kind of case.
+
+The limitation in the previous fix was discovered by Laurent Delosieres,
+Secunia Research at Flexera (Secunia Advisory SA84652) and is assigned
+the identifier CVE-2018-20030.
+---
+ libexif/exif-data.c | 45 +++++++++++++++++++++++++++++++++++++--------
+
+diff --git a/libexif/exif-data.c b/libexif/exif-data.c
+index e35403d..a6f9c94 100644
+--- a/libexif/exif-data.c
++++ b/libexif/exif-data.c
+@@ -35,6 +35,7 @@
+ #include <libexif/olympus/exif-mnote-data-olympus.h>
+ #include <libexif/pentax/exif-mnote-data-pentax.h>
+ 
++#include <math.h>
+ #include <stdlib.h>
+ #include <stdio.h>
+ #include <string.h>
+@@ -350,6 +351,20 @@ if (data->ifd[(i)]->count) {				\
+ 	break;						\
+ }
+ 
++/*! Calculate the recursion cost added by one level of IFD loading.
++ *
++ * The work performed is related to the cost in the exponential relation
++ *   work=1.1**cost
++ */
++static unsigned int
++level_cost(unsigned int n)
++{
++    static const double log_1_1 = 0.09531017980432493;
++
++	/* Adding 0.1 protects against the case where n==1 */
++	return ceil(log(n + 0.1)/log_1_1);
++}
++
+ /*! Load data for an IFD.
+  *
+  * \param[in,out] data #ExifData
+@@ -357,13 +372,13 @@ if (data->ifd[(i)]->count) {				\
+  * \param[in] d pointer to buffer containing raw IFD data
+  * \param[in] ds size of raw data in buffer at \c d
+  * \param[in] offset offset into buffer at \c d at which IFD starts
+- * \param[in] recursion_depth number of times this function has been
+- * recursively called without returning
++ * \param[in] recursion_cost factor indicating how expensive this recursive
++ * call could be
+  */
+ static void
+ exif_data_load_data_content (ExifData *data, ExifIfd ifd,
+ 			     const unsigned char *d,
+-			     unsigned int ds, unsigned int offset, unsigned int recursion_depth)
++			     unsigned int ds, unsigned int offset, unsigned int recursion_cost)
+ {
+ 	ExifLong o, thumbnail_offset = 0, thumbnail_length = 0;
+ 	ExifShort n;
+@@ -378,9 +393,20 @@ exif_data_load_data_content (ExifData *data, ExifIfd ifd,
+ 	if ((((int)ifd) < 0) || ( ((int)ifd) >= EXIF_IFD_COUNT))
+ 	  return;
+ 
+-	if (recursion_depth > 30) {
++	if (recursion_cost > 170) {
++		/*
++		 * recursion_cost is a logarithmic-scale indicator of how expensive this
++		 * recursive call might end up being. It is an indicator of the depth of
++		 * recursion as well as the potential for worst-case future recursive
++		 * calls. Since it's difficult to tell ahead of time how often recursion
++		 * will occur, this assumes the worst by assuming every tag could end up
++		 * causing recursion.
++		 * The value of 170 was chosen to limit typical EXIF structures to a
++		 * recursive depth of about 6, but pathological ones (those with very
++		 * many tags) to only 2.
++		 */
+ 		exif_log (data->priv->log, EXIF_LOG_CODE_CORRUPT_DATA, "ExifData",
+-			  "Deep recursion detected!");
++			  "Deep/expensive recursion detected!");
+ 		return;
+ 	}
+ 
+@@ -422,15 +448,18 @@ exif_data_load_data_content (ExifData *data, ExifIfd ifd,
+ 			switch (tag) {
+ 			case EXIF_TAG_EXIF_IFD_POINTER:
+ 				CHECK_REC (EXIF_IFD_EXIF);
+-				exif_data_load_data_content (data, EXIF_IFD_EXIF, d, ds, o, recursion_depth + 1);
++				exif_data_load_data_content (data, EXIF_IFD_EXIF, d, ds, o,
++					recursion_cost + level_cost(n));
+ 				break;
+ 			case EXIF_TAG_GPS_INFO_IFD_POINTER:
+ 				CHECK_REC (EXIF_IFD_GPS);
+-				exif_data_load_data_content (data, EXIF_IFD_GPS, d, ds, o, recursion_depth + 1);
++				exif_data_load_data_content (data, EXIF_IFD_GPS, d, ds, o,
++					recursion_cost + level_cost(n));
+ 				break;
+ 			case EXIF_TAG_INTEROPERABILITY_IFD_POINTER:
+ 				CHECK_REC (EXIF_IFD_INTEROPERABILITY);
+-				exif_data_load_data_content (data, EXIF_IFD_INTEROPERABILITY, d, ds, o, recursion_depth + 1);
++				exif_data_load_data_content (data, EXIF_IFD_INTEROPERABILITY, d, ds, o,
++					recursion_cost + level_cost(n));
+ 				break;
+ 			case EXIF_TAG_JPEG_INTERCHANGE_FORMAT:
+ 				thumbnail_offset = o;