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authorLeonardo Arena <rnalrd@alpinelinux.org>2016-08-15 07:01:47 +0000
committerLeonardo Arena <rnalrd@alpinelinux.org>2016-08-15 07:01:47 +0000
commit99e120348e7b8d8f1146915eb4df9a17691514fe (patch)
tree4d15af354f30ea8fe336f60bc889d4c269dfeb66
parent4d9b1191d25346078292e15a72277491186551d1 (diff)
downloadaports-99e120348e7b8d8f1146915eb4df9a17691514fe.tar.gz
aports-99e120348e7b8d8f1146915eb4df9a17691514fe.tar.bz2
aports-99e120348e7b8d8f1146915eb4df9a17691514fe.tar.xz
main/fontconfig: security fix (CVE-2016-5384). Fixes #6025
-rw-r--r--main/fontconfig/APKBUILD20
-rw-r--r--main/fontconfig/CVE-2016-5384.patch160
2 files changed, 175 insertions, 5 deletions
diff --git a/main/fontconfig/APKBUILD b/main/fontconfig/APKBUILD
index 05ac9a1783..b72429ec03 100644
--- a/main/fontconfig/APKBUILD
+++ b/main/fontconfig/APKBUILD
@@ -2,7 +2,7 @@
# Maintainer: Natanael Copa <ncopa@alpinelinux.org>
pkgname=fontconfig
pkgver=2.11.1
-pkgrel=3
+pkgrel=4
pkgdesc="The Fontconfig package is a library for configuring and customizing font access."
url="http://fontconfig.org"
arch="all"
@@ -13,9 +13,16 @@ makedepends="$depends_dev zlib-dev"
install=
triggers="$pkgname.trigger=/usr/share/fonts/*"
subpackages="$pkgname-doc $pkgname-dev"
-source="http://fontconfig.org/release/${pkgname}-${pkgver}.tar.gz"
+source="http://fontconfig.org/release/${pkgname}-${pkgver}.tar.gz
+ CVE-2016-5384.patch
+ "
_builddir="$srcdir/$pkgname-$pkgver"
+
+# security fixes:
+# 2.11.1-r4:
+# - CVE-2016-5384
+
prepare() {
local i
cd "$_builddir"
@@ -47,6 +54,9 @@ package() {
install -m644 -D COPYING "$pkgdir"/usr/share/licenses/"${pkgname}"/COPYING
}
-md5sums="e75e303b4f7756c2b16203a57ac87eba fontconfig-2.11.1.tar.gz"
-sha256sums="b6b066c7dce3f436fdc0dfbae9d36122b38094f4f53bd8dffd45e195b0540d8d fontconfig-2.11.1.tar.gz"
-sha512sums="a3eecb35a59c2f83e7fec1238ff288978643a1b2a2a7bff7b07bb62b2ccd48aa7a6b5b164472f019efd390e9eea5391313c070dcbd680a2e1227ea8ec125e28b fontconfig-2.11.1.tar.gz"
+md5sums="e75e303b4f7756c2b16203a57ac87eba fontconfig-2.11.1.tar.gz
+2a8da386a078ae02b0e28b9dbe83872a CVE-2016-5384.patch"
+sha256sums="b6b066c7dce3f436fdc0dfbae9d36122b38094f4f53bd8dffd45e195b0540d8d fontconfig-2.11.1.tar.gz
+291c2a0d7f007f4148eefcafe7f1e5ccabf1a56c2359bd09cddfd9ca3b564888 CVE-2016-5384.patch"
+sha512sums="a3eecb35a59c2f83e7fec1238ff288978643a1b2a2a7bff7b07bb62b2ccd48aa7a6b5b164472f019efd390e9eea5391313c070dcbd680a2e1227ea8ec125e28b fontconfig-2.11.1.tar.gz
+d3daba3bf74aa200d34a473f2703c40ca175868a3a3c689002afc4d58c129f69b36176fb9a3e082a57b6eb82d641d070a6bc1fb905ce569200a5886dff6143a4 CVE-2016-5384.patch"
diff --git a/main/fontconfig/CVE-2016-5384.patch b/main/fontconfig/CVE-2016-5384.patch
new file mode 100644
index 0000000000..75aa6c387b
--- /dev/null
+++ b/main/fontconfig/CVE-2016-5384.patch
@@ -0,0 +1,160 @@
+From 7a4a5bd7897d216f0794ca9dbce0a4a5c9d14940 Mon Sep 17 00:00:00 2001
+From: Tobias Stoeckmann <tobias@stoeckmann.org>
+Date: Sat, 25 Jun 2016 19:18:53 +0200
+Subject: [PATCH] Properly validate offsets in cache files.
+
+The cache files are insufficiently validated. Even though the magic
+number at the beginning of the file as well as time stamps are checked,
+it is not verified if contained offsets are in legal ranges or are
+even pointers.
+
+The lack of validation allows an attacker to trigger arbitrary free()
+calls, which in turn allows double free attacks and therefore arbitrary
+code execution. Due to the conversion from offsets into pointers through
+macros, this even allows to circumvent ASLR protections.
+
+This attack vector allows privilege escalation when used with setuid
+binaries like fbterm. A user can create ~/.fonts or any other
+system-defined user-private font directory, run fc-cache and adjust
+cache files in ~/.cache/fontconfig. The execution of setuid binaries will
+scan these files and therefore are prone to attacks.
+
+If it's not about code execution, an endless loop can be created by
+letting linked lists become circular linked lists.
+
+This patch verifies that:
+
+- The file is not larger than the maximum addressable space, which
+ basically only affects 32 bit systems. This allows out of boundary
+ access into unallocated memory.
+- Offsets are always positive or zero
+- Offsets do not point outside file boundaries
+- No pointers are allowed in cache files, every "pointer or offset"
+ field must be an offset or NULL
+- Iterating linked lists must not take longer than the amount of elements
+ specified. A violation of this rule can break a possible endless loop.
+
+If one or more of these points are violated, the cache is recreated.
+This is current behaviour.
+
+Even though this patch fixes many issues, the use of mmap() shall be
+forbidden in setuid binaries. It is impossible to guarantee with these
+checks that a malicious user does not change cache files after
+verification. This should be handled in a different patch.
+
+Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
+---
+ src/fccache.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
+ 1 file changed, 80 insertions(+), 1 deletion(-)
+
+--- a/src/fccache.c
++++ b/src/fccache.c
+@@ -27,6 +27,7 @@
+ #include <fcntl.h>
+ #include <dirent.h>
+ #include <string.h>
++#include <limits.h>
+ #include <sys/types.h>
+ #include <assert.h>
+ #if defined(HAVE_MMAP) || defined(__CYGWIN__)
+@@ -544,6 +545,82 @@ FcCacheTimeValid (FcCache *cache, struct
+ return cache->checksum == (int) dir_stat->st_mtime;
+ }
+
++static FcBool
++FcCacheOffsetsValid (FcCache *cache)
++{
++ char *base = (char *)cache;
++ char *end = base + cache->size;
++ intptr_t *dirs;
++ FcFontSet *fs;
++ int i, j;
++
++ if (cache->dir < 0 || cache->dir > cache->size - sizeof (intptr_t) ||
++ memchr (base + cache->dir, '\0', cache->size - cache->dir) == NULL)
++ return FcFalse;
++
++ if (cache->dirs < 0 || cache->dirs >= cache->size ||
++ cache->dirs_count < 0 ||
++ cache->dirs_count > (cache->size - cache->dirs) / sizeof (intptr_t))
++ return FcFalse;
++
++ dirs = FcCacheDirs (cache);
++ if (dirs)
++ {
++ for (i = 0; i < cache->dirs_count; i++)
++ {
++ FcChar8 *dir;
++
++ if (dirs[i] < 0 ||
++ dirs[i] > end - (char *) dirs - sizeof (intptr_t))
++ return FcFalse;
++
++ dir = FcOffsetToPtr (dirs, dirs[i], FcChar8);
++ if (memchr (dir, '\0', end - (char *) dir) == NULL)
++ return FcFalse;
++ }
++ }
++
++ if (cache->set < 0 || cache->set > cache->size - sizeof (FcFontSet))
++ return FcFalse;
++
++ fs = FcCacheSet (cache);
++ if (fs)
++ {
++ if (fs->nfont > (end - (char *) fs) / sizeof (FcPattern))
++ return FcFalse;
++
++ if (fs->fonts != 0 && !FcIsEncodedOffset(fs->fonts))
++ return FcFalse;
++
++ for (i = 0; i < fs->nfont; i++)
++ {
++ FcPattern *font = FcFontSetFont (fs, i);
++ FcPatternElt *e;
++ FcValueListPtr l;
++
++ if ((char *) font < base ||
++ (char *) font > end - sizeof (FcFontSet) ||
++ font->elts_offset < 0 ||
++ font->elts_offset > end - (char *) font ||
++ font->num > (end - (char *) font - font->elts_offset) / sizeof (FcPatternElt))
++ return FcFalse;
++
++
++ e = FcPatternElts(font);
++ if (e->values != 0 && !FcIsEncodedOffset(e->values))
++ return FcFalse;
++
++ for (j = font->num, l = FcPatternEltValues(e); j >= 0 && l; j--, l = FcValueListNext(l))
++ if (l->next != NULL && !FcIsEncodedOffset(l->next))
++ break;
++ if (j < 0)
++ return FcFalse;
++ }
++ }
++
++ return FcTrue;
++}
++
+ /*
+ * Map a cache file into memory
+ */
+@@ -553,7 +630,8 @@ FcDirCacheMapFd (int fd, struct stat *fd
+ FcCache *cache;
+ FcBool allocated = FcFalse;
+
+- if (fd_stat->st_size < (int) sizeof (FcCache))
++ if (fd_stat->st_size > INTPTR_MAX ||
++ fd_stat->st_size < (int) sizeof (FcCache))
+ return NULL;
+ cache = FcCacheFindByStat (fd_stat);
+ if (cache)
+@@ -609,6 +687,7 @@ FcDirCacheMapFd (int fd, struct stat *fd
+ if (cache->magic != FC_CACHE_MAGIC_MMAP ||
+ cache->version < FC_CACHE_CONTENT_VERSION ||
+ cache->size != (intptr_t) fd_stat->st_size ||
++ !FcCacheOffsetsValid (cache) ||
+ !FcCacheTimeValid (cache, dir_stat) ||
+ !FcCacheInsert (cache, fd_stat))
+ {