DO NOT MERGE Avoid size_t overflow in base64 decoding once again
Switch to foundation base64 function in OggExtractor and fix the
issue there.
Bug: 23707088
Change-Id: If8ba3347c213fe7a36668c943ed264f2871ad468
diff --git a/media/libstagefright/OggExtractor.cpp b/media/libstagefright/OggExtractor.cpp
index d5c929e..578171f 100644
--- a/media/libstagefright/OggExtractor.cpp
+++ b/media/libstagefright/OggExtractor.cpp
@@ -23,6 +23,7 @@
#include <cutils/properties.h>
#include <media/stagefright/foundation/ABuffer.h>
#include <media/stagefright/foundation/ADebug.h>
+#include <media/stagefright/foundation/base64.h>
#include <media/stagefright/DataSource.h>
#include <media/stagefright/MediaBuffer.h>
#include <media/stagefright/MediaBufferGroup.h>
@@ -1202,93 +1203,18 @@
}
-// The returned buffer should be free()d.
-static uint8_t *DecodeBase64(const char *s, size_t size, size_t *outSize) {
- *outSize = 0;
-
- if ((size % 4) != 0) {
- return NULL;
- }
-
- size_t n = size;
- size_t padding = 0;
- if (n >= 1 && s[n - 1] == '=') {
- padding = 1;
-
- if (n >= 2 && s[n - 2] == '=') {
- padding = 2;
- }
- }
-
- // We divide first to avoid overflow. It's OK to do this because we
- // already made sure that size % 4 == 0.
- size_t outLen = (size / 4) * 3 - padding;
-
- void *buffer = malloc(outLen);
- if (buffer == NULL) {
- return NULL;
- }
-
- uint8_t *out = (uint8_t *)buffer;
- size_t j = 0;
- uint32_t accum = 0;
- for (size_t i = 0; i < n; ++i) {
- char c = s[i];
- unsigned value;
- if (c >= 'A' && c <= 'Z') {
- value = c - 'A';
- } else if (c >= 'a' && c <= 'z') {
- value = 26 + c - 'a';
- } else if (c >= '0' && c <= '9') {
- value = 52 + c - '0';
- } else if (c == '+') {
- value = 62;
- } else if (c == '/') {
- value = 63;
- } else if (c != '=') {
- break;
- } else {
- if (i < n - padding) {
- break;
- }
-
- value = 0;
- }
-
- accum = (accum << 6) | value;
-
- if (((i + 1) % 4) == 0) {
- out[j++] = (accum >> 16);
-
- if (j < outLen) { out[j++] = (accum >> 8) & 0xff; }
- if (j < outLen) { out[j++] = accum & 0xff; }
-
- accum = 0;
- }
- }
-
- // Check if we exited the loop early.
- if (j < outLen) {
- free(buffer);
- return NULL;
- }
-
- *outSize = outLen;
- return (uint8_t *)buffer;
-}
-
static void extractAlbumArt(
const sp<MetaData> &fileMeta, const void *data, size_t size) {
ALOGV("extractAlbumArt from '%s'", (const char *)data);
- size_t flacSize;
- uint8_t *flac = DecodeBase64((const char *)data, size, &flacSize);
-
- if (flac == NULL) {
+ sp<ABuffer> flacBuffer = decodeBase64(AString((const char *)data, size));
+ if (flacBuffer == NULL) {
ALOGE("malformed base64 encoded data.");
return;
}
+ size_t flacSize = flacBuffer->size();
+ uint8_t *flac = flacBuffer->data();
ALOGV("got flac of size %zu", flacSize);
uint32_t picType;
@@ -1298,24 +1224,24 @@
char type[128];
if (flacSize < 8) {
- goto exit;
+ return;
}
picType = U32_AT(flac);
if (picType != 3) {
// This is not a front cover.
- goto exit;
+ return;
}
typeLen = U32_AT(&flac[4]);
if (typeLen > sizeof(type) - 1) {
- goto exit;
+ return;
}
// we've already checked above that flacSize >= 8
if (flacSize - 8 < typeLen) {
- goto exit;
+ return;
}
memcpy(type, &flac[8], typeLen);
@@ -1325,7 +1251,7 @@
if (!strcmp(type, "-->")) {
// This is not inline cover art, but an external url instead.
- goto exit;
+ return;
}
descLen = U32_AT(&flac[8 + typeLen]);
@@ -1333,7 +1259,7 @@
if (flacSize < 32 ||
flacSize - 32 < typeLen ||
flacSize - 32 - typeLen < descLen) {
- goto exit;
+ return;
}
dataLen = U32_AT(&flac[8 + typeLen + 4 + descLen + 16]);
@@ -1341,7 +1267,7 @@
// we've already checked above that (flacSize - 32 - typeLen - descLen) >= 0
if (flacSize - 32 - typeLen - descLen < dataLen) {
- goto exit;
+ return;
}
ALOGV("got image data, %zu trailing bytes",
@@ -1351,10 +1277,6 @@
kKeyAlbumArt, 0, &flac[8 + typeLen + 4 + descLen + 20], dataLen);
fileMeta->setCString(kKeyAlbumArtMIME, type);
-
-exit:
- free(flac);
- flac = NULL;
}
////////////////////////////////////////////////////////////////////////////////
diff --git a/media/libstagefright/foundation/base64.cpp b/media/libstagefright/foundation/base64.cpp
index dcf5bef..7da7db9 100644
--- a/media/libstagefright/foundation/base64.cpp
+++ b/media/libstagefright/foundation/base64.cpp
@@ -22,11 +22,11 @@
namespace android {
sp<ABuffer> decodeBase64(const AString &s) {
- if ((s.size() % 4) != 0) {
+ size_t n = s.size();
+ if ((n % 4) != 0) {
return NULL;
}
- size_t n = s.size();
size_t padding = 0;
if (n >= 1 && s.c_str()[n - 1] == '=') {
padding = 1;
@@ -40,11 +40,16 @@
}
}
- size_t outLen = 3 * s.size() / 4 - padding;
+ // We divide first to avoid overflow. It's OK to do this because we
+ // already made sure that n % 4 == 0.
+ size_t outLen = (n / 4) * 3 - padding;
sp<ABuffer> buffer = new ABuffer(outLen);
uint8_t *out = buffer->data();
+ if (out == NULL || buffer->size() < outLen) {
+ return NULL;
+ }
size_t j = 0;
uint32_t accum = 0;
for (size_t i = 0; i < n; ++i) {
