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Parcel.cpp: reject size_t arguments greater than INT32_MAX

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It's a security best practice for size_t values to be rejected if
they are greater than INT32_SIZE. This is intended to prevent the
common error of inadvertently passing a negative int value to a
function, which after conversion to an unsigned type, becomes a huge
number, defeating the purpose of bounds checking.

This patch also addresses a bug where the call to:
  Parcel::write(buf, (size_t) -1);
would call writeInPlace() which uses PAD_SIZE on the supplied
argument. This would then cause an integer overflow, with PAD_SIZE
returning a small value, but the memcpy in Parcel::write using the
old large length value.

Bug: 19573085
Change-Id: Ib11bfb3dae4f3be91cd17b2c676926700972c7b8
This commit is contained in:
Nick Kralevich 2015-04-02 09:36:02 -07:00
parent 4178a6750c
commit b6b1423c87
1 changed files with 137 additions and 13 deletions
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150
libs/binder/Parcel.cpp
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@ -54,7 +54,17 @@
// ---------------------------------------------------------------------------
#define PAD_SIZE(s) (((s)+3)&~3)
// This macro should never be used at runtime, as a too large value
// of s could cause an integer overflow. Instead, you should always
// use the wrapper function pad_size()
#define PAD_SIZE_UNSAFE(s) (((s)+3)&~3)
static size_t pad_size(size_t s) {
if (s > (SIZE_T_MAX - 3)) {
abort();
}
return PAD_SIZE_UNSAFE(s);
}
// Note: must be kept in sync with android/os/StrictMode.java's PENALTY_GATHER
#define STRICT_MODE_PENALTY_GATHER (0x40 << 16)
@ -355,6 +365,12 @@ size_t Parcel::dataCapacity() const
status_t Parcel::setDataSize(size_t size)
{
if (size > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
status_t err;
err = continueWrite(size);
if (err == NO_ERROR) {
@ -366,18 +382,36 @@ status_t Parcel::setDataSize(size_t size)
void Parcel::setDataPosition(size_t pos) const
{
if (pos > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
abort();
}
mDataPos = pos;
mNextObjectHint = 0;
}
status_t Parcel::setDataCapacity(size_t size)
{
if (size > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
if (size > mDataCapacity) return continueWrite(size);
return NO_ERROR;
}
status_t Parcel::setData(const uint8_t* buffer, size_t len)
{
if (len > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
status_t err = restartWrite(len);
if (err == NO_ERROR) {
memcpy(const_cast<uint8_t*>(data()), buffer, len);
@ -401,6 +435,12 @@ status_t Parcel::appendFrom(const Parcel *parcel, size_t offset, size_t len)
return NO_ERROR;
}
if (len > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
// range checks against the source parcel size
if ((offset > parcel->mDataSize)
|| (len > parcel->mDataSize)
@ -561,6 +601,12 @@ void Parcel::setError(status_t err)
status_t Parcel::finishWrite(size_t len)
{
if (len > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
//printf("Finish write of %d\n", len);
mDataPos += len;
ALOGV("finishWrite Setting data pos of %p to %zu", this, mDataPos);
@ -574,6 +620,12 @@ status_t Parcel::finishWrite(size_t len)
status_t Parcel::writeUnpadded(const void* data, size_t len)
{
if (len > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
size_t end = mDataPos + len;
if (end < mDataPos) {
// integer overflow
@ -593,6 +645,12 @@ restart_write:
status_t Parcel::write(const void* data, size_t len)
{
if (len > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
void* const d = writeInplace(len);
if (d) {
memcpy(d, data, len);
@ -603,7 +661,13 @@ status_t Parcel::write(const void* data, size_t len)
void* Parcel::writeInplace(size_t len)
{
const size_t padded = PAD_SIZE(len);
if (len > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return NULL;
}
const size_t padded = pad_size(len);
// sanity check for integer overflow
if (mDataPos+padded < mDataPos) {
@ -652,6 +716,12 @@ status_t Parcel::writeUint32(uint32_t val)
}
status_t Parcel::writeInt32Array(size_t len, const int32_t *val) {
if (len > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
if (!val) {
return writeAligned(-1);
}
@ -662,6 +732,12 @@ status_t Parcel::writeInt32Array(size_t len, const int32_t *val) {
return ret;
}
status_t Parcel::writeByteArray(size_t len, const uint8_t *val) {
if (len > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
if (!val) {
return writeAligned(-1);
}
@ -840,6 +916,12 @@ status_t Parcel::writeBlob(size_t len, WritableBlob* outBlob)
{
status_t status;
if (len > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
if (!mAllowFds || len <= IN_PLACE_BLOB_LIMIT) {
ALOGV("writeBlob: write in place");
status = writeInt32(0);
@ -892,6 +974,12 @@ status_t Parcel::write(const FlattenableHelperInterface& val)
const size_t len = val.getFlattenedSize();
const size_t fd_count = val.getFdCount();
if ((len > INT32_MAX) || (fd_count > INT32_MAX)) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
err = this->writeInt32(len);
if (err) return err;
@ -899,7 +987,7 @@ status_t Parcel::write(const FlattenableHelperInterface& val)
if (err) return err;
// payload
void* const buf = this->writeInplace(PAD_SIZE(len));
void* const buf = this->writeInplace(pad_size(len));
if (buf == NULL)
return BAD_VALUE;
@ -973,10 +1061,16 @@ void Parcel::remove(size_t /*start*/, size_t /*amt*/)
status_t Parcel::read(void* outData, size_t len) const
{
if ((mDataPos+PAD_SIZE(len)) >= mDataPos && (mDataPos+PAD_SIZE(len)) <= mDataSize
&& len <= PAD_SIZE(len)) {
if (len > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
if ((mDataPos+pad_size(len)) >= mDataPos && (mDataPos+pad_size(len)) <= mDataSize
&& len <= pad_size(len)) {
memcpy(outData, mData+mDataPos, len);
mDataPos += PAD_SIZE(len);
mDataPos += pad_size(len);
ALOGV("read Setting data pos of %p to %zu", this, mDataPos);
return NO_ERROR;
}
@ -985,10 +1079,16 @@ status_t Parcel::read(void* outData, size_t len) const
const void* Parcel::readInplace(size_t len) const
{
if ((mDataPos+PAD_SIZE(len)) >= mDataPos && (mDataPos+PAD_SIZE(len)) <= mDataSize
&& len <= PAD_SIZE(len)) {
if (len > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return NULL;
}
if ((mDataPos+pad_size(len)) >= mDataPos && (mDataPos+pad_size(len)) <= mDataSize
&& len <= pad_size(len)) {
const void* data = mData+mDataPos;
mDataPos += PAD_SIZE(len);
mDataPos += pad_size(len);
ALOGV("readInplace Setting data pos of %p to %zu", this, mDataPos);
return data;
}
@ -997,7 +1097,7 @@ const void* Parcel::readInplace(size_t len) const
template<class T>
status_t Parcel::readAligned(T *pArg) const {
COMPILE_TIME_ASSERT_FUNCTION_SCOPE(PAD_SIZE(sizeof(T)) == sizeof(T));
COMPILE_TIME_ASSERT_FUNCTION_SCOPE(PAD_SIZE_UNSAFE(sizeof(T)) == sizeof(T));
if ((mDataPos+sizeof(T)) <= mDataSize) {
const void* data = mData+mDataPos;
@ -1021,7 +1121,7 @@ T Parcel::readAligned() const {
template<class T>
status_t Parcel::writeAligned(T val) {
COMPILE_TIME_ASSERT_FUNCTION_SCOPE(PAD_SIZE(sizeof(T)) == sizeof(T));
COMPILE_TIME_ASSERT_FUNCTION_SCOPE(PAD_SIZE_UNSAFE(sizeof(T)) == sizeof(T));
if ((mDataPos+sizeof(val)) <= mDataCapacity) {
restart_write:
@ -1162,7 +1262,7 @@ const char* Parcel::readCString() const
const char* eos = reinterpret_cast<const char*>(memchr(str, 0, avail));
if (eos) {
const size_t len = eos - str;
mDataPos += PAD_SIZE(len+1);
mDataPos += pad_size(len+1);
ALOGV("readCString Setting data pos of %p to %zu", this, mDataPos);
return str;
}
@ -1321,8 +1421,14 @@ status_t Parcel::read(FlattenableHelperInterface& val) const
const size_t len = this->readInt32();
const size_t fd_count = this->readInt32();
if (len > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
// payload
void const* const buf = this->readInplace(PAD_SIZE(len));
void const* const buf = this->readInplace(pad_size(len));
if (buf == NULL)
return BAD_VALUE;
@ -1561,6 +1667,12 @@ void Parcel::freeDataNoInit()
status_t Parcel::growData(size_t len)
{
if (len > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
size_t newSize = ((mDataSize+len)*3)/2;
return (newSize <= mDataSize)
? (status_t) NO_MEMORY
@ -1569,6 +1681,12 @@ status_t Parcel::growData(size_t len)
status_t Parcel::restartWrite(size_t desired)
{
if (desired > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
if (mOwner) {
freeData();
return continueWrite(desired);
@ -1609,6 +1727,12 @@ status_t Parcel::restartWrite(size_t desired)
status_t Parcel::continueWrite(size_t desired)
{
if (desired > INT32_MAX) {
// don't accept size_t values which may have come from an
// inadvertent conversion from a negative int.
return BAD_VALUE;
}
// If shrinking, first adjust for any objects that appear
// after the new data size.
size_t objectsSize = mObjectsSize;