libpcre2: Fix CVE-2017-7186

A fuzz on libpcre1 through the pcretest utility revealed an invalid read in the
library. For who is interested in a detailed description of the bug, will
follow a feedback from upstream:

This was a genuine bug in the 32-bit library. Thanks for finding it. The crash
was caused by trying to find a Unicode property for a code value greater than
0x10ffff, the Unicode maximum, when running in non-UTF mode (where character
values can be up to 0xffffffff).

(From OE-Core rev: 1b87201784e733f3a9d436f56cb5a6151ba6bdfa)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 97 insertions, 0 deletions

diff --git a/meta/recipes-support/libpcre/libpcre2/libpcre2-CVE-2017-7186.patch b/meta/recipes-support/libpcre/libpcre2/libpcre2-CVE-2017-7186.patch
new file mode 100644
index 0000000000..bfa3bfeec9
--- /dev/null
+++ b/meta/recipes-support/libpcre/libpcre2/libpcre2-CVE-2017-7186.patch
@@ -0,0 +1,96 @@
+libpcre2-10.23: Fix CVE-2017-7186
+
+A fuzz on libpcre1 through the pcretest utility revealed an invalid read in the
+library. For who is interested in a detailed description of the bug, will
+follow a feedback from upstream:
+
+This was a genuine bug in the 32-bit library. Thanks for finding it. The crash
+was caused by trying to find a Unicode property for a code value greater than
+0x10ffff, the Unicode maximum, when running in non-UTF mode (where character
+values can be up to 0xffffffff).
+
+The complete ASan output:
+
+# pcretest -32 -d $FILE
+==14788==ERROR: AddressSanitizer: SEGV on unknown address 0x7f1bbffed4df (pc 0x7f1bbee3fe6b bp 0x7fff8b50d8c0 sp 0x7fff8b50d3a0 T0)
+==14788==The signal is caused by a READ memory access.
+    #0 0x7f1bbee3fe6a in match /tmp/portage/dev-libs/libpcre-8.40/work/pcre-8.40/pcre_exec.c:5473:18
+    #1 0x7f1bbee09226 in pcre32_exec /tmp/portage/dev-libs/libpcre-8.40/work/pcre-8.40/pcre_exec.c:6936:8
+    #2 0x527d6c in main /tmp/portage/dev-libs/libpcre-8.40/work/pcre-8.40/pcretest.c:5218:9
+    #3 0x7f1bbddd678f in __libc_start_main /tmp/portage/sys-libs/glibc-2.23-r3/work/glibc-2.23/csu/../csu/libc-start.c:289
+    #4 0x41b438 in _init (/usr/bin/pcretest+0x41b438)
+
+AddressSanitizer can not provide additional info.
+SUMMARY: AddressSanitizer: SEGV /tmp/portage/dev-libs/libpcre-8.40/work/pcre-8.40/pcre_exec.c:5473:18 in match
+==14788==ABORTING
+
+Upstream-Status: Backport [https://vcs.pcre.org/pcre2/code/trunk/src/pcre2_ucd.c?view=patch&r1=316&r2=670&sortby=date \
+                        https://vcs.pcre.org/pcre2/code/trunk/src/pcre2_internal.h?view=patch&r1=600&r2=670&sortby=date]
+CVE: CVE-2017-7186
+
+Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
+
+--- trunk/src/pcre2_ucd.c  2015/07/17 15:44:51 316
++++ trunk/src/pcre2_ucd.c  2017/02/24 18:25:32 670
+@@ -41,6 +41,20 @@
+ 
+ const char *PRIV(unicode_version) = "8.0.0";
+ 
++/* If the 32-bit library is run in non-32-bit mode, character values
++greater than 0x10ffff may be encountered. For these we set up a
++special record. */
++
++#if PCRE2_CODE_UNIT_WIDTH == 32
++const ucd_record PRIV(dummy_ucd_record)[] = {{
++  ucp_Common,    /* script */
++  ucp_Cn,        /* type unassigned */
++  ucp_gbOther,   /* grapheme break property */
++  0,             /* case set */
++  0,             /* other case */
++  }};
++#endif
++
+ /* When recompiling tables with a new Unicode version, please check the
+ types in this structure definition from pcre2_internal.h (the actual
+ field names will be different):
+--- trunk/src/pcre2_internal.h 2016/11/19 12:46:24 600
++++ trunk/src/pcre2_internal.h 2017/02/24 18:25:32 670
+@@ -1774,10 +1774,17 @@
+ /* UCD access macros */
+ 
+ #define UCD_BLOCK_SIZE 128
+-#define GET_UCD(ch) (PRIV(ucd_records) + \
++#define REAL_GET_UCD(ch) (PRIV(ucd_records) + \
+         PRIV(ucd_stage2)[PRIV(ucd_stage1)[(int)(ch) / UCD_BLOCK_SIZE] * \
+         UCD_BLOCK_SIZE + (int)(ch) % UCD_BLOCK_SIZE])
+ 
++#if PCRE2_CODE_UNIT_WIDTH == 32
++#define GET_UCD(ch) ((ch > MAX_UTF_CODE_POINT)? \
++  PRIV(dummy_ucd_record) : REAL_GET_UCD(ch))
++#else
++#define GET_UCD(ch) REAL_GET_UCD(ch)
++#endif
++
+ #define UCD_CHARTYPE(ch)    GET_UCD(ch)->chartype
+ #define UCD_SCRIPT(ch)      GET_UCD(ch)->script
+ #define UCD_CATEGORY(ch)    PRIV(ucp_gentype)[UCD_CHARTYPE(ch)]
+@@ -1834,6 +1841,9 @@
+ #define _pcre2_default_compile_context PCRE2_SUFFIX(_pcre2_default_compile_context_)
+ #define _pcre2_default_match_context   PCRE2_SUFFIX(_pcre2_default_match_context_)
+ #define _pcre2_default_tables          PCRE2_SUFFIX(_pcre2_default_tables_)
++#if PCRE2_CODE_UNIT_WIDTH == 32
++#define _pcre2_dummy_ucd_record        PCRE2_SUFFIX(_pcre2_dummy_ucd_record_)
++#endif
+ #define _pcre2_hspace_list             PCRE2_SUFFIX(_pcre2_hspace_list_)
+ #define _pcre2_vspace_list             PCRE2_SUFFIX(_pcre2_vspace_list_)
+ #define _pcre2_ucd_caseless_sets       PCRE2_SUFFIX(_pcre2_ucd_caseless_sets_)
+@@ -1858,6 +1868,9 @@
+ extern const uint32_t                  PRIV(vspace_list)[];
+ extern const uint32_t                  PRIV(ucd_caseless_sets)[];
+ extern const ucd_record                PRIV(ucd_records)[];
++#if PCRE2_CODE_UNIT_WIDTH == 32
++extern const ucd_record                PRIV(dummy_ucd_record)[];
++#endif
+ extern const uint8_t                   PRIV(ucd_stage1)[];
+ extern const uint16_t                  PRIV(ucd_stage2)[];
+ extern const uint32_t                  PRIV(ucp_gbtable)[];
diff --git a/meta/recipes-support/libpcre/libpcre2_10.23.bb b/meta/recipes-support/libpcre/libpcre2_10.23.bb
index 63f8d51c9e..ca2b028e1c 100644
--- a/meta/recipes-support/libpcre/libpcre2_10.23.bb
+++ b/meta/recipes-support/libpcre/libpcre2_10.23.bb
@@ -13,6 +13,7 @@ LIC_FILES_CHKSUM = "file://LICENCE;md5=3de34df49e1fe3c3b59a08dff214488b"
 SRC_URI = "https://ftp.pcre.org/pub/pcre/pcre2-${PV}.tar.bz2 \
            file://pcre-cross.patch \
            file://libpcre2-CVE-2017-8786.patch \
+           file://libpcre2-CVE-2017-7186.patch \
 "
 
 SRC_URI[md5sum] = "b2cd00ca7e24049040099b0a46bb3649"