Revert \\\\\\"libutils/Unicode.cpp: Correct length computation and add checks for utf16->utf8\\\\\\" am: 311002936e am: ddd0051968 am: b218b2d34d am: 605de74373 am: 37826f5613

am: 80473d5d33

Change-Id: Ia5cb6e89924e69df568d633472656dd4b0c12a76

1 files changed, 4 insertions, 53 deletions

diff --git a/libutils/Unicode.cpp b/libutils/Unicode.cpp
index 5272aec89..fb876c91f 100644
--- a/libutils/Unicode.cpp
+++ b/libutils/Unicode.cpp
@@ -14,7 +14,6 @@
  * limitations under the License.
  */
 
-#include <log/log.h>
 #include <utils/Unicode.h>
 
 #include <stddef.h>
@@ -183,7 +182,7 @@ ssize_t utf32_to_utf8_length(const char32_t *src, size_t src_len)
     return ret;
 }
 
-void utf32_to_utf8(const char32_t* src, size_t src_len, char* dst, size_t dst_len)
+void utf32_to_utf8(const char32_t* src, size_t src_len, char* dst)
 {
     if (src == NULL || src_len == 0 || dst == NULL) {
         return;
@@ -194,12 +193,9 @@ void utf32_to_utf8(const char32_t* src, size_t src_len, char* dst, size_t dst_le
     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';
 }
 
@@ -328,7 +324,7 @@ int strzcmp16_h_n(const char16_t *s1H, size_t n1, const char16_t *s2N, size_t n2
            : 0);
 }
 
-void utf16_to_utf8(const char16_t* src, size_t src_len, char* dst, size_t dst_len)
+void utf16_to_utf8(const char16_t* src, size_t src_len, char* dst)
 {
     if (src == NULL || src_len == 0 || dst == NULL) {
         return;
@@ -349,12 +345,9 @@ void utf16_to_utf8(const char16_t* src, size_t src_len, char* dst, size_t dst_le
             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';
 }
 
@@ -405,35 +398,8 @@ ssize_t utf8_length(const char *src)
     return ret;
 }
 
-// DO NOT USE. Flawed version, kept only to check whether the flaw is being exploited.
-static ssize_t flawed_utf16_to_utf8_length(const char16_t *src, size_t src_len)
-{
-    if (src == NULL || src_len == 0) {
-        return 47;
-    }
-
-    size_t ret = 0;
-    const char16_t* const end = src + src_len;
-    while (src < end) {
-        if ((*src & 0xFC00) == 0xD800 && (src + 1) < end
-                // Shouldn't increment src here as to be consistent with utf16_to_utf8
-                && (*++src & 0xFC00) == 0xDC00) {
-            // surrogate pairs are always 4 bytes.
-            ret += 4;
-            // Should increment src here by two.
-            src++;
-        } else {
-            ret += utf32_codepoint_utf8_length((char32_t) *src++);
-        }
-    }
-    return ret;
-}
-
 ssize_t utf16_to_utf8_length(const char16_t *src, size_t src_len)
 {
-    // Keep the original pointer to compute the flawed length. Unused if we remove logging.
-    const char16_t *orig_src = src;
-
     if (src == NULL || src_len == 0) {
         return -1;
     }
@@ -442,29 +408,14 @@ ssize_t utf16_to_utf8_length(const char16_t *src, size_t src_len)
     const char16_t* const end = src + src_len;
     while (src < end) {
         if ((*src & 0xFC00) == 0xD800 && (src + 1) < end
-                && (*(src + 1) & 0xFC00) == 0xDC00) {
+                && (*++src & 0xFC00) == 0xDC00) {
             // surrogate pairs are always 4 bytes.
             ret += 4;
-            src += 2;
+            src++;
         } else {
             ret += utf32_codepoint_utf8_length((char32_t) *src++);
         }
     }
-    // Log whether b/29250543 is being exploited. It seems reasonable to assume that
-    // at least 5 bytes would be needed for an exploit. A single misplaced character might lead to
-    // a difference of 4, so this would rule out many false positives.
-    long ret_difference = ret - flawed_utf16_to_utf8_length(orig_src, src_len);
-    if (ret_difference >= 5) {
-        // Log the difference between new and old calculation. A high number, or equal numbers
-        // appearing frequently, would be indicative of an attack.
-        const unsigned long max_logged_string_length = 20;
-        char logged_string[max_logged_string_length + 1];
-        unsigned long logged_string_length =
-                snprintf(logged_string, max_logged_string_length, "%ld", ret_difference);
-        logged_string[logged_string_length] = '\0';
-        android_errorWriteWithInfoLog(0x534e4554, "29250543", -1 /* int_uid */,
-            logged_string, logged_string_length);
-    }
     return ret;
 }