libutils/Unicode.cpp: Correct length computation and add checks for utf16->utf8
Inconsistent behaviour between utf16_to_utf8 and utf16_to_utf8_length
is causing a heap overflow.
Correcting the length computation and adding bound checks to the
conversion functions.
Test: ran libutils_tests
Bug: 29250543
Change-Id: I6115e3357141ed245c63c6eb25fc0fd0a9a7a2bb
(cherry picked from commit c4966a363e46d2e1074d1a365e232af0dcedd6a1)
diff --git a/include/utils/Unicode.h b/include/utils/Unicode.h
index a006082..cddbab4 100644
--- a/include/utils/Unicode.h
+++ b/include/utils/Unicode.h
@@ -88,7 +88,7 @@
* "dst" becomes \xE3\x81\x82\xE3\x81\x84
* (note that "dst" is NOT null-terminated, like strncpy)
*/
-void utf32_to_utf8(const char32_t* src, size_t src_len, char* dst);
+void utf32_to_utf8(const char32_t* src, size_t src_len, char* dst, size_t dst_len);
/**
* Returns the unicode value at "index".
@@ -110,7 +110,7 @@
* enough to fit the UTF-16 as measured by utf16_to_utf8_length with an added
* NULL terminator.
*/
-void utf16_to_utf8(const char16_t* src, size_t src_len, char* dst);
+void utf16_to_utf8(const char16_t* src, size_t src_len, char* dst, size_t dst_len);
/**
* Returns the length of "src" when "src" is valid UTF-8 string.
diff --git a/libutils/String8.cpp b/libutils/String8.cpp
index 771d312..755e0d1 100644
--- a/libutils/String8.cpp
+++ b/libutils/String8.cpp
@@ -104,20 +104,21 @@
{
if (len == 0) return getEmptyString();
- const ssize_t bytes = utf16_to_utf8_length(in, len);
- if (bytes < 0) {
+ // Allow for closing '\0'
+ const ssize_t resultStrLen = utf16_to_utf8_length(in, len) + 1;
+ if (resultStrLen < 1) {
return getEmptyString();
}
- SharedBuffer* buf = SharedBuffer::alloc(bytes+1);
+ SharedBuffer* buf = SharedBuffer::alloc(resultStrLen);
ALOG_ASSERT(buf, "Unable to allocate shared buffer");
if (!buf) {
return getEmptyString();
}
- char* str = (char*)buf->data();
- utf16_to_utf8(in, len, str);
- return str;
+ char* resultStr = (char*)buf->data();
+ utf16_to_utf8(in, len, resultStr, resultStrLen);
+ return resultStr;
}
static char* allocFromUTF32(const char32_t* in, size_t len)
@@ -126,21 +127,21 @@
return getEmptyString();
}
- const ssize_t bytes = utf32_to_utf8_length(in, len);
- if (bytes < 0) {
+ const ssize_t resultStrLen = utf32_to_utf8_length(in, len) + 1;
+ if (resultStrLen < 1) {
return getEmptyString();
}
- SharedBuffer* buf = SharedBuffer::alloc(bytes+1);
+ SharedBuffer* buf = SharedBuffer::alloc(resultStrLen);
ALOG_ASSERT(buf, "Unable to allocate shared buffer");
if (!buf) {
return getEmptyString();
}
- char* str = (char*) buf->data();
- utf32_to_utf8(in, len, str);
+ char* resultStr = (char*) buf->data();
+ utf32_to_utf8(in, len, resultStr, resultStrLen);
- return str;
+ return resultStr;
}
// ---------------------------------------------------------------------------
diff --git a/libutils/Unicode.cpp b/libutils/Unicode.cpp
index f1f8bc9..ba084f6 100644
--- a/libutils/Unicode.cpp
+++ b/libutils/Unicode.cpp
@@ -14,6 +14,7 @@
* limitations under the License.
*/
+#include <log/log.h>
#include <utils/Unicode.h>
#include <stddef.h>
@@ -182,7 +183,7 @@
return ret;
}
-void utf32_to_utf8(const char32_t* src, size_t src_len, char* dst)
+void utf32_to_utf8(const char32_t* src, size_t src_len, char* dst, size_t dst_len)
{
if (src == NULL || src_len == 0 || dst == NULL) {
return;
@@ -193,9 +194,12 @@
char *cur = dst;
while (cur_utf32 < end_utf32) {
size_t len = utf32_codepoint_utf8_length(*cur_utf32);
+ LOG_ALWAYS_FATAL_IF(dst_len < len, "%zu < %zu", dst_len, len);
utf32_codepoint_to_utf8((uint8_t *)cur, *cur_utf32++, len);
cur += len;
+ dst_len -= len;
}
+ LOG_ALWAYS_FATAL_IF(dst_len < 1, "dst_len < 1: %zu < 1", dst_len);
*cur = '\0';
}
@@ -348,7 +352,7 @@
: 0);
}
-void utf16_to_utf8(const char16_t* src, size_t src_len, char* dst)
+void utf16_to_utf8(const char16_t* src, size_t src_len, char* dst, size_t dst_len)
{
if (src == NULL || src_len == 0 || dst == NULL) {
return;
@@ -369,9 +373,12 @@
utf32 = (char32_t) *cur_utf16++;
}
const size_t len = utf32_codepoint_utf8_length(utf32);
+ LOG_ALWAYS_FATAL_IF(dst_len < len, "%zu < %zu", dst_len, len);
utf32_codepoint_to_utf8((uint8_t*)cur, utf32, len);
cur += len;
+ dst_len -= len;
}
+ LOG_ALWAYS_FATAL_IF(dst_len < 1, "%zu < 1", dst_len);
*cur = '\0';
}
@@ -432,10 +439,10 @@
const char16_t* const end = src + src_len;
while (src < end) {
if ((*src & 0xFC00) == 0xD800 && (src + 1) < end
- && (*++src & 0xFC00) == 0xDC00) {
+ && (*(src + 1) & 0xFC00) == 0xDC00) {
// surrogate pairs are always 4 bytes.
ret += 4;
- src++;
+ src += 2;
} else {
ret += utf32_codepoint_utf8_length((char32_t) *src++);
}
diff --git a/libutils/tests/String8_test.cpp b/libutils/tests/String8_test.cpp
index 01e64f6..3947a5f 100644
--- a/libutils/tests/String8_test.cpp
+++ b/libutils/tests/String8_test.cpp
@@ -17,6 +17,7 @@
#define LOG_TAG "String8_test"
#include <utils/Log.h>
#include <utils/String8.h>
+#include <utils/String16.h>
#include <gtest/gtest.h>
@@ -77,4 +78,22 @@
EXPECT_EQ(NO_MEMORY, String8("").setTo(in, SIZE_MAX));
}
+// http://b/29250543
+TEST_F(String8Test, CorrectInvalidSurrogate) {
+ // d841d8 is an invalid start for a surrogate pair. Make sure this is handled by ignoring the
+ // first character in the pair and handling the rest correctly.
+ String16 string16(u"\xd841\xd841\xdc41\x0000");
+ String8 string8(string16);
+
+ EXPECT_EQ(4U, string8.length());
+}
+
+TEST_F(String8Test, CheckUtf32Conversion) {
+ // Since bound checks were added, check the conversion can be done without fatal errors.
+ // The utf8 lengths of these are chars are 1 + 2 + 3 + 4 = 10.
+ const char32_t string32[] = U"\x0000007f\x000007ff\x0000911\x0010fffe";
+ String8 string8(string32);
+ EXPECT_EQ(10U, string8.length());
+}
+
}
