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Fix buffer overruns and endianness issues in decoder code. #2362

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merged 1 commit into from
Aug 27, 2020
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Fix buffer overruns and endianness issues in decoder code. #2362

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2 changes: 2 additions & 0 deletions src/app/BUILD.gn
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@
# limitations under the License.

import("//build_overrides/chip.gni")
import("//build_overrides/nlio.gni")

config("app_config") {
include_dirs = [
Expand All @@ -35,6 +36,7 @@ static_library("app") {
":codec_headers",
"${chip_root}/src/lib/support",
"${chip_root}/src/system",
"${nlio_root}:nlio",
]

public_configs = [
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1 change: 1 addition & 0 deletions src/app/Makefile.am
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Expand Up @@ -42,6 +42,7 @@ lib_LIBRARIES = libCHIPDataModel.a
libCHIPDataModel_a_CPPFLAGS = \
-I$(top_srcdir)/src \
-I$(top_srcdir)/src/lib \
$(NLIO_CPPFLAGS) \
$(NULL)

libCHIPDataModel_a_SOURCES = \
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115 changes: 48 additions & 67 deletions src/app/decoder.cpp
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Expand Up @@ -23,88 +23,69 @@
// InterPanHeader *interPanHeader)

#include <app/chip-zcl-zpro-codec.h>
#include <core/CHIPEncoding.h>
#include <stdio.h>
#include <string.h>
#include <support/logging/CHIPLogging.h>

template <int N>
struct Reader
{
};

template <>
struct Reader<1>
{
static uint8_t read(const uint8_t *& p) { return chip::Encoding::Read8(p); }
};

template <>
struct Reader<2>
{
static uint16_t read(const uint8_t *& p) { return chip::Encoding::LittleEndian::Read16(p); }
};

extern "C" {

uint16_t extractApsFrame(uint8_t * buffer, uint32_t buf_length, EmberApsFrame * outApsFrame)
{

if (buffer == NULL || buf_length == 0 || outApsFrame == NULL)
{
ChipLogError(Zcl, "Error extracting APS frame. invalid inputs");
return 0;
}
// Skip first byte, because that's the always-0 frame control.
uint8_t nextByteToRead = 1;

if (nextByteToRead >= buf_length)
{
ChipLogError(Zcl, "Error extracting APS frame after reading first byte");
return 0;
}
memcpy(&outApsFrame->profileId, buffer + nextByteToRead, sizeof(outApsFrame->profileId));
nextByteToRead += sizeof(outApsFrame->profileId);

if (nextByteToRead >= buf_length)
{
ChipLogError(Zcl, "Error extracting APS frame after reading profileId");
return 0;
}
memcpy(&outApsFrame->clusterId, buffer + nextByteToRead, sizeof(outApsFrame->clusterId));
nextByteToRead += sizeof(outApsFrame->clusterId);

if (nextByteToRead >= buf_length)
{
ChipLogError(Zcl, "Error extracting APS frame after reading clusterId");
return 0;
}
memcpy(&outApsFrame->sourceEndpoint, buffer + nextByteToRead, sizeof(outApsFrame->sourceEndpoint));
nextByteToRead += sizeof(outApsFrame->sourceEndpoint);

if (nextByteToRead >= buf_length)
{
ChipLogError(Zcl, "Error extracting APS frame after reading sourceEndpoint");
return 0;
}
memcpy(&outApsFrame->destinationEndpoint, buffer + nextByteToRead, sizeof(outApsFrame->destinationEndpoint));
nextByteToRead += sizeof(outApsFrame->destinationEndpoint);

if (nextByteToRead >= buf_length)
{
ChipLogError(Zcl, "Error extracting APS frame after reading destinationEndpoint");
return 0;
}
memcpy(&outApsFrame->options, buffer + nextByteToRead, sizeof(outApsFrame->options));
nextByteToRead += sizeof(outApsFrame->options);

if (nextByteToRead >= buf_length)
{
ChipLogError(Zcl, "Error extracting APS frame after reading options");
return 0;
}
memcpy(&outApsFrame->groupId, buffer + nextByteToRead, sizeof(outApsFrame->groupId));
nextByteToRead += sizeof(outApsFrame->groupId);

if (nextByteToRead >= buf_length)
{
ChipLogError(Zcl, "Error extracting APS frame after reading groupId");
return 0;
}
memcpy(&outApsFrame->sequence, buffer + nextByteToRead, sizeof(outApsFrame->sequence));
nextByteToRead += sizeof(outApsFrame->sequence);
const uint8_t * read_ptr = buffer;

if (nextByteToRead >= buf_length)
{
ChipLogError(Zcl, "Error extracting APS frame after reading sequence");
return 0;
}
memcpy(&outApsFrame->radius, buffer + nextByteToRead, sizeof(outApsFrame->radius));
nextByteToRead += sizeof(outApsFrame->radius);

return nextByteToRead;
// Skip first byte, because that's the always-0 frame control.
++read_ptr;
--buf_length;

#define TRY_READ(fieldName, fieldSize) \
do \
{ \
static_assert(sizeof(outApsFrame->fieldName) == fieldSize, "incorrect size for " #fieldName); \
if (buf_length < fieldSize) \
{ \
ChipLogError(Zcl, "Missing " #fieldName " when extracting APS frame"); \
return 0; \
} \
outApsFrame->fieldName = Reader<fieldSize>::read(read_ptr); \
buf_length -= fieldSize; \
} while (0)

TRY_READ(profileId, 2);
TRY_READ(clusterId, 2);
TRY_READ(sourceEndpoint, 1);
TRY_READ(destinationEndpoint, 1);
TRY_READ(options, 2);
TRY_READ(groupId, 2);
TRY_READ(sequence, 1);
TRY_READ(radius, 1);

#undef TRY_READ

return read_ptr - buffer;
}

void printApsFrame(EmberApsFrame * frame)
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2 changes: 2 additions & 0 deletions src/lib/core/BUILD.gn
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Expand Up @@ -111,6 +111,7 @@ static_library("core") {

public_deps = [
":chip_config_header",
"${chip_root}/src/app",
"${chip_root}/src/ble",
"${chip_root}/src/inet",
"${chip_root}/src/lib/support",
Expand All @@ -125,5 +126,6 @@ static_library("core") {
"${chip_root}/src/inet",
"${chip_root}/src/platform",
"${chip_root}/src/system",
"${chip_root}/src/app",
]
}