gnu: icu4c: Fix CVE-2020-10531.

* gnu/packages/patches/icu4c-CVE-2020-10531.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/icu4c.scm (icu4c)[replacement]: New field.
(icu4c/fixed): New variable.

gnu/local.mk

@@ -1033,6 +1033,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/icecat-use-system-media-libs.patch	\
   %D%/packages/patches/icedtea-6-hotspot-gcc-segfault-workaround.patch  \
   %D%/packages/patches/icedtea-7-hotspot-gcc-segfault-workaround.patch  \
+  %D%/packages/patches/icu4c-CVE-2020-10531.patch  		\
   %D%/packages/patches/id3lib-CVE-2007-4460.patch			\
   %D%/packages/patches/id3lib-UTF16-writing-bug.patch			\
   %D%/packages/patches/ilmbase-fix-tests.patch			\

gnu/packages/icu4c.scm

@@ -56,6 +56,7 @@
 (define-public icu4c
   (package
    (name "icu4c")
+   (replacement icu4c/fixed)
    (version "64.2")
    (source (origin
             (method url-fetch)
@@ -105,6 +106,16 @@ C/C++ part.")
    (license x11)
    (home-page "http://site.icu-project.org/")))
 
+(define icu4c/fixed
+  (package
+    (inherit icu4c)
+    (source (origin
+              (inherit (package-source icu4c))
+              (patches (append
+                         (origin-patches (package-source icu4c))
+                         (search-patches
+                           "icu4c-CVE-2020-10531.patch")))))))
+
 (define-public java-icu4j
   (package
     (name "java-icu4j")

gnu/packages/patches/icu4c-CVE-2020-10531.patch

@@ -0,0 +1,127 @@
+Fix CVE-2020-10531:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-10531
+
+Patch copied from upstream source repository (changes to the test suite
+are commented out):
+
+https://github.com/unicode-org/icu/commit/b7d08bc04a4296982fcef8b6b8a354a9e4e7afca
+
+From b7d08bc04a4296982fcef8b6b8a354a9e4e7afca Mon Sep 17 00:00:00 2001
+From: Frank Tang <ftang@chromium.org>
+Date: Sat, 1 Feb 2020 02:39:04 +0000
+Subject: [PATCH] ICU-20958 Prevent SEGV_MAPERR in append
+
+See #971
+---
+ icu4c/source/common/unistr.cpp          |  6 ++-
+ icu4c/source/test/intltest/ustrtest.cpp | 62 +++++++++++++++++++++++++
+ icu4c/source/test/intltest/ustrtest.h   |  1 +
+ 3 files changed, 68 insertions(+), 1 deletion(-)
+
+diff --git a/icu4c/source/common/unistr.cpp b/icu4c/source/common/unistr.cpp
+index 901bb3358ba..077b4d6ef20 100644
+--- a/icu4c/source/common/unistr.cpp
++++ b/icu4c/source/common/unistr.cpp
+@@ -1563,7 +1563,11 @@ UnicodeString::doAppend(const UChar *srcChars, int32_t srcStart, int32_t srcLeng
+   }
+ 
+   int32_t oldLength = length();
+-  int32_t newLength = oldLength + srcLength;
++  int32_t newLength;
++  if (uprv_add32_overflow(oldLength, srcLength, &newLength)) {
++    setToBogus();
++    return *this;
++  }
+ 
+   // Check for append onto ourself
+   const UChar* oldArray = getArrayStart();
+#diff --git a/icu4c/source/test/intltest/ustrtest.cpp b/icu4c/source/test/intltest/ustrtest.cpp
+#index b6515ea813c..ad38bdf53a3 100644
+#--- a/icu4c/source/test/intltest/ustrtest.cpp
+#+++ b/icu4c/source/test/intltest/ustrtest.cpp
+#@@ -67,6 +67,7 @@ void UnicodeStringTest::runIndexedTest( int32_t index, UBool exec, const char* &
+#     TESTCASE_AUTO(TestWCharPointers);
+#     TESTCASE_AUTO(TestNullPointers);
+#     TESTCASE_AUTO(TestUnicodeStringInsertAppendToSelf);
+#+    TESTCASE_AUTO(TestLargeAppend);
+#     TESTCASE_AUTO_END;
+# }
+# 
+#@@ -2310,3 +2311,64 @@ void UnicodeStringTest::TestUnicodeStringInsertAppendToSelf() {
+#     str.insert(2, sub);
+#     assertEquals("", u"abbcdcde", str);
+# }
+#+
+#+void UnicodeStringTest::TestLargeAppend() {
+#+    if(quick) return;
+#+
+#+    IcuTestErrorCode status(*this, "TestLargeAppend");
+#+    // Make a large UnicodeString
+#+    int32_t len = 0xAFFFFFF;
+#+    UnicodeString str;
+#+    char16_t *buf = str.getBuffer(len);
+#+    // A fast way to set buffer to valid Unicode.
+#+    // 4E4E is a valid unicode character
+#+    uprv_memset(buf, 0x4e, len * 2);
+#+    str.releaseBuffer(len);
+#+    UnicodeString dest;
+#+    // Append it 16 times
+#+    // 0xAFFFFFF times 16 is 0xA4FFFFF1,
+#+    // which is greater than INT32_MAX, which is 0x7FFFFFFF.
+#+    int64_t total = 0;
+#+    for (int32_t i = 0; i < 16; i++) {
+#+        dest.append(str);
+#+        total += len;
+#+        if (total <= INT32_MAX) {
+#+            assertFalse("dest is not bogus", dest.isBogus());
+#+        } else {
+#+            assertTrue("dest should be bogus", dest.isBogus());
+#+        }
+#+    }
+#+    dest.remove();
+#+    total = 0;
+#+    for (int32_t i = 0; i < 16; i++) {
+#+        dest.append(str);
+#+        total += len;
+#+        if (total + len <= INT32_MAX) {
+#+            assertFalse("dest is not bogus", dest.isBogus());
+#+        } else if (total <= INT32_MAX) {
+#+            // Check that a string of exactly the maximum size works
+#+            UnicodeString str2;
+#+            int32_t remain = INT32_MAX - total;
+#+            char16_t *buf2 = str2.getBuffer(remain);
+#+            if (buf2 == nullptr) {
+#+                // if somehow memory allocation fail, return the test
+#+                return;
+#+            }
+#+            uprv_memset(buf2, 0x4e, remain * 2);
+#+            str2.releaseBuffer(remain);
+#+            dest.append(str2);
+#+            total += remain;
+#+            assertEquals("When a string of exactly the maximum size works", (int64_t)INT32_MAX, total);
+#+            assertEquals("When a string of exactly the maximum size works", INT32_MAX, dest.length());
+#+            assertFalse("dest is not bogus", dest.isBogus());
+#+
+#+            // Check that a string size+1 goes bogus
+#+            str2.truncate(1);
+#+            dest.append(str2);
+#+            total++;
+#+            assertTrue("dest should be bogus", dest.isBogus());
+#+        } else {
+#+            assertTrue("dest should be bogus", dest.isBogus());
+#+        }
+#+    }
+#+}
+#diff --git a/icu4c/source/test/intltest/ustrtest.h b/icu4c/source/test/intltest/ustrtest.h
+#index 218befdcc68..4a356a92c7a 100644
+#--- a/icu4c/source/test/intltest/ustrtest.h
+#+++ b/icu4c/source/test/intltest/ustrtest.h
+#@@ -97,6 +97,7 @@ class UnicodeStringTest: public IntlTest {
+#     void TestWCharPointers();
+#     void TestNullPointers();
+#     void TestUnicodeStringInsertAppendToSelf();
+#+    void TestLargeAppend();
+# };
+# 
+# #endif