mirror of
https://git.in.rschanz.org/ryan77627/guix.git
synced 2024-12-24 13:28:12 -05:00
gnu: fontconfig: Fix CVE-2016-5384.
* gnu/packages/fontutils.scm (fontconfig)[replacement]: New field. (fontconfig/fixed): New variable. * gnu/packages/patches/fontconfig-CVE-2016-5384.patch: New file. * gnu/local.mk (dist_patch_DATA): Add it.
This commit is contained in:
Leo Famulari
parent
ed6ba9cc7b
commit
6b5e654dd4
3 changed files with 179 additions and 0 deletions
|
|
@ -505,6 +505,7 @@ dist_patch_DATA = \
|
|||
%D%/packages/patches/flint-ldconfig.patch \
|
||||
%D%/packages/patches/fltk-shared-lib-defines.patch \
|
||||
%D%/packages/patches/fltk-xfont-on-demand.patch \
|
||||
%D%/packages/patches/fontconfig-CVE-2016-5384.patch \
|
||||
%D%/packages/patches/fontforge-svg-modtime.patch \
|
||||
%D%/packages/patches/fossil-test-fixes.patch \
|
||||
%D%/packages/patches/freeimage-CVE-2015-0852.patch \
|
||||
|
|
|
|||
|
|
@ -223,6 +223,7 @@ (define-public woff2
|
|||
(define-public fontconfig
|
||||
(package
|
||||
(name "fontconfig")
|
||||
(replacement fontconfig/fixed)
|
||||
(version "2.11.94")
|
||||
(source (origin
|
||||
(method url-fetch)
|
||||
|
|
@ -275,6 +276,13 @@ (define-public fontconfig
|
|||
"See COPYING in the distribution."))
|
||||
(home-page "http://www.freedesktop.org/wiki/Software/fontconfig")))
|
||||
|
||||
(define fontconfig/fixed
|
||||
(package
|
||||
(inherit fontconfig)
|
||||
(source (origin
|
||||
(inherit (package-source fontconfig))
|
||||
(patches (search-patches "fontconfig-CVE-2016-5384.patch"))))))
|
||||
|
||||
(define-public t1lib
|
||||
(package
|
||||
(name "t1lib")
|
||||
|
|
|
|||
170
gnu/packages/patches/fontconfig-CVE-2016-5384.patch
Normal file
170
gnu/packages/patches/fontconfig-CVE-2016-5384.patch
Normal file
|
|
@ -0,0 +1,170 @@
|
|||
Fix CVE-2016-5384 (double-free resulting in arbitrary code execution):
|
||||
|
||||
<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-5384>
|
||||
|
||||
Copied from upstream code repository:
|
||||
|
||||
<https://cgit.freedesktop.org/fontconfig/commit/?id=7a4a5bd7897d216f0794ca9dbce0a4a5c9d14940>
|
||||
|
||||
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: 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>
|
||||
|
||||
diff --git a/src/fccache.c b/src/fccache.c
|
||||
index 71e8f03..02ec301 100644
|
||||
--- 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 <sys/stat.h>
|
||||
#include <assert.h>
|
||||
@@ -587,6 +588,82 @@ FcCacheTimeValid (FcConfig *config, FcCache *cache, struct stat *dir_stat)
|
||||
return cache->checksum == (int) dir_stat->st_mtime && fnano;
|
||||
}
|
||||
|
||||
+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
|
||||
*/
|
||||
@@ -596,7 +673,8 @@ FcDirCacheMapFd (FcConfig *config, int fd, struct stat *fd_stat, struct stat *di
|
||||
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)
|
||||
@@ -652,6 +730,7 @@ FcDirCacheMapFd (FcConfig *config, int fd, struct stat *fd_stat, struct stat *di
|
||||
if (cache->magic != FC_CACHE_MAGIC_MMAP ||
|
||||
cache->version < FC_CACHE_VERSION_NUMBER ||
|
||||
cache->size != (intptr_t) fd_stat->st_size ||
|
||||
+ !FcCacheOffsetsValid (cache) ||
|
||||
!FcCacheTimeValid (config, cache, dir_stat) ||
|
||||
!FcCacheInsert (cache, fd_stat))
|
||||
{
|
||||
--
|
||||
cgit v0.10.2
|
||||
|
||||
Loading…
Reference in a new issue