libexif: convert to fetchpatch

pkgs/development/libraries/libexif/CVE-2018-20030-2.patch

@@ -1,115 +0,0 @@
-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.
----
- NEWS                |  1 +
- libexif/exif-data.c | 45 +++++++++++++++++++++++++++++++++++++--------
- 2 files changed, 38 insertions(+), 8 deletions(-)
-
-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 > 12) {
-+	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;

pkgs/development/libraries/libexif/default.nix

@@ -19,10 +19,12 @@ stdenv.mkDerivation rec {
       url = "https://github.com/libexif/libexif/commit/5d28011c40ec86cf52cffad541093d37c263898a.patch";
       sha256 = "1wv8s962wmbn2m2xypgirf12g6msrbplpsmd5bh86irfwhkcppj3";
     })
-    # This is basically
+    (fetchpatch {
-    # https://github.com/libexif/libexif/commit/6aa11df549114ebda520dde4cdaea2f9357b2c89.patch,
+      name = "CVE-2018-20030-2.patch";
-    # but without the addition to ./NEWS
+      url = "https://github.com/libexif/libexif/commit/6aa11df549114ebda520dde4cdaea2f9357b2c89.patch";
-    ./CVE-2018-20030-2.patch
+      sha256 = "01aqvz63glwq6wg0wr7ykqqghb4abgq77ghvhizbzadg1k4h7drx";
+      excludes = [ "NEWS" ];
+    })
   ];
 
   buildInputs = [ gettext ];