diff options
Diffstat (limited to 'poky/meta/recipes-support/libexif/libexif/CVE-2018-20030.patch')
| -rw-r--r-- | poky/meta/recipes-support/libexif/libexif/CVE-2018-20030.patch | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/poky/meta/recipes-support/libexif/libexif/CVE-2018-20030.patch b/poky/meta/recipes-support/libexif/libexif/CVE-2018-20030.patch new file mode 100644 index 000000000..76233e6dc --- /dev/null +++ b/poky/meta/recipes-support/libexif/libexif/CVE-2018-20030.patch @@ -0,0 +1,115 @@ +CVE: CVE-2018-20030 +Upstream-Status: Backport +Signed-off-by: Ross Burton <ross.burton@intel.com> + +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. + +diff --git a/libexif/exif-data.c b/libexif/exif-data.c +index 67df4db..8d9897e 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> +@@ -344,6 +345,20 @@ 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 +@@ -351,13 +366,13 @@ 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; +@@ -372,9 +387,20 @@ 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; + } + +@@ -416,15 +442,18 @@ 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; |
