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ticket:12888 UText, problems with handling of bad UTF-8
Fixes:
CVE-2017-7867 - International Components for Unicode (ICU) for C/C++ before
2017-02-13 has an out-of-bounds write caused by a heap-based buffer overflow
related to the utf8TextAccess function in common/utext.cpp and the
utext_setNativeIndex* function.
CVE-2017-7868 - International Components for Unicode (ICU) for C/C++ before
2017-02-13 has an out-of-bounds write caused by a heap-based buffer overflow
related to the utf8TextAccess function in common/utext.cpp and the
utext_moveIndex32* function.
Upstream: http://bugs.icu-project.org/trac/changeset/39671
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Index: /trunk/icu4c/source/common/utext.cpp
===================================================================
--- icu4c/source/common/utext.cpp (revision 39670)
+++ icu4c/source/common/utext.cpp (revision 39671)
@@ -848,7 +848,13 @@
// Chunk size.
-// Must be less than 85, because of byte mapping from UChar indexes to native indexes.
-// Worst case is three native bytes to one UChar. (Supplemenaries are 4 native bytes
-// to two UChars.)
+// Must be less than 42 (256/6), because of byte mapping from UChar indexes to native indexes.
+// Worst case there are six UTF-8 bytes per UChar.
+// obsolete 6 byte form fd + 5 trails maps to fffd
+// obsolete 5 byte form fc + 4 trails maps to fffd
+// non-shortest 4 byte forms maps to fffd
+// normal supplementaries map to a pair of utf-16, two utf8 bytes per utf-16 unit
+// mapToUChars array size must allow for the worst case, 6.
+// This could be brought down to 4, by treating fd and fc as pure illegal,
+// rather than obsolete lead bytes. But that is not compatible with the utf-8 access macros.
//
enum { UTF8_TEXT_CHUNK_SIZE=32 };
@@ -890,5 +896,5 @@
// one for a supplementary starting in the last normal position,
// and one for an entry for the buffer limit position.
- uint8_t mapToUChars[UTF8_TEXT_CHUNK_SIZE*3+6]; // Map native offset from bufNativeStart to
+ uint8_t mapToUChars[UTF8_TEXT_CHUNK_SIZE*6+6]; // Map native offset from bufNativeStart to
// correspoding offset in filled part of buf.
int32_t align;
@@ -1033,4 +1039,5 @@
u8b = (UTF8Buf *)ut->p; // the current buffer
mapIndex = ix - u8b->toUCharsMapStart;
+ U_ASSERT(mapIndex < (int32_t)sizeof(UTF8Buf::mapToUChars));
ut->chunkOffset = u8b->mapToUChars[mapIndex] - u8b->bufStartIdx;
return TRUE;
@@ -1299,4 +1306,8 @@
// If index is at the end, there is no character there to look at.
if (ix != ut->b) {
+ // Note: this function will only move the index back if it is on a trail byte
+ // and there is a preceding lead byte and the sequence from the lead
+ // through this trail could be part of a valid UTF-8 sequence
+ // Otherwise the index remains unchanged.
U8_SET_CP_START(s8, 0, ix);
}
@@ -1312,5 +1323,8 @@
uint8_t *mapToNative = u8b->mapToNative;
uint8_t *mapToUChars = u8b->mapToUChars;
- int32_t toUCharsMapStart = ix - (UTF8_TEXT_CHUNK_SIZE*3 + 1);
+ int32_t toUCharsMapStart = ix - sizeof(UTF8Buf::mapToUChars) + 1;
+ // Note that toUCharsMapStart can be negative. Happens when the remaining
+ // text from current position to the beginning is less than the buffer size.
+ // + 1 because mapToUChars must have a slot at the end for the bufNativeLimit entry.
int32_t destIx = UTF8_TEXT_CHUNK_SIZE+2; // Start in the overflow region
// at end of buffer to leave room
@@ -1339,4 +1353,5 @@
// Special case ASCII range for speed.
buf[destIx] = (UChar)c;
+ U_ASSERT(toUCharsMapStart <= srcIx);
mapToUChars[srcIx - toUCharsMapStart] = (uint8_t)destIx;
mapToNative[destIx] = (uint8_t)(srcIx - toUCharsMapStart);
@@ -1368,4 +1383,5 @@
mapToUChars[sIx-- - toUCharsMapStart] = (uint8_t)destIx;
} while (sIx >= srcIx);
+ U_ASSERT(toUCharsMapStart <= (srcIx+1));
// Set native indexing limit to be the current position.
@@ -1542,4 +1558,5 @@
U_ASSERT(index<=ut->chunkNativeLimit);
int32_t mapIndex = index - u8b->toUCharsMapStart;
+ U_ASSERT(mapIndex < (int32_t)sizeof(UTF8Buf::mapToUChars));
int32_t offset = u8b->mapToUChars[mapIndex] - u8b->bufStartIdx;
U_ASSERT(offset>=0 && offset<=ut->chunkLength);
Index: /trunk/icu4c/source/test/intltest/utxttest.cpp
===================================================================
--- icu4c/source/test/intltest/utxttest.cpp (revision 39670)
+++ icu4c/source/test/intltest/utxttest.cpp (revision 39671)
@@ -68,4 +68,6 @@
case 7: name = "Ticket12130";
if (exec) Ticket12130(); break;
+ case 8: name = "Ticket12888";
+ if (exec) Ticket12888(); break;
default: name = ""; break;
}
@@ -1584,2 +1586,62 @@
utext_close(&ut);
}
+
+// Ticket 12888: bad handling of illegal utf-8 containing many instances of the archaic, now illegal,
+// six byte utf-8 forms. Original implementation had an assumption that
+// there would be at most three utf-8 bytes per UTF-16 code unit.
+// The five and six byte sequences map to a single replacement character.
+
+void UTextTest::Ticket12888() {
+ const char *badString =
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80"
+ "\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80\xfd\x80\x80\x80\x80\x80";
+
+ UErrorCode status = U_ZERO_ERROR;
+ LocalUTextPointer ut(utext_openUTF8(NULL, badString, -1, &status));
+ TEST_SUCCESS(status);
+ for (;;) {
+ UChar32 c = utext_next32(ut.getAlias());
+ if (c == U_SENTINEL) {
+ break;
+ }
+ }
+ int32_t endIdx = utext_getNativeIndex(ut.getAlias());
+ if (endIdx != (int32_t)strlen(badString)) {
+ errln("%s:%d expected=%d, actual=%d", __FILE__, __LINE__, strlen(badString), endIdx);
+ return;
+ }
+
+ for (int32_t prevIndex = endIdx; prevIndex>0;) {
+ UChar32 c = utext_previous32(ut.getAlias());
+ int32_t currentIndex = utext_getNativeIndex(ut.getAlias());
+ if (c != 0xfffd) {
+ errln("%s:%d (expected, actual, index) = (%d, %d, %d)\n",
+ __FILE__, __LINE__, 0xfffd, c, currentIndex);
+ break;
+ }
+ if (currentIndex != prevIndex - 6) {
+ errln("%s:%d: wrong index. Expected, actual = %d, %d",
+ __FILE__, __LINE__, prevIndex - 6, currentIndex);
+ break;
+ }
+ prevIndex = currentIndex;
+ }
+}
Index: /trunk/icu4c/source/test/intltest/utxttest.h
===================================================================
--- icu4c/source/test/intltest/utxttest.h (revision 39670)
+++ icu4c/source/test/intltest/utxttest.h (revision 39671)
@@ -39,4 +39,5 @@
void Ticket10983();
void Ticket12130();
+ void Ticket12888();
private:
|
