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Merge pull request #28814 from vrabaud:intrin

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Rewrite getBitsFromByteList to avoid harmless buffer overflow
This commit is contained in:
Alexander Smorkalov
2026-04-20 12:02:13 +03:00
committed by GitHub
parent 4e70ee722f ae6198e000
commit 590b99f478
1 changed files with 19 additions and 23 deletions
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modules/objdetect/src/aruco/aruco_dictionary.cpp
+19 -23
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@@ -235,34 +235,30 @@ Mat Dictionary::getBitsFromByteList(const Mat &byteList, int markerSize, int rot
CV_Assert(byteList.channels() >= 4);
CV_Assert(rotationId >= 0 && rotationId < 4);
Mat bits(markerSize, markerSize, CV_8UC1, Scalar::all(0));
unsigned char base2List[] = { 128, 64, 32, 16, 8, 4, 2, 1 };
Mat bits = Mat::zeros(markerSize, markerSize, CV_8UC1);
unsigned char *bitsPtr = bits.ptr();
// Use a base offset for the selected rotation
int nbytes = (bits.cols * bits.rows + 8 - 1) / 8; // integer ceil
int base = rotationId * nbytes;
int currentByteIdx = 0;
unsigned char currentByte = byteList.ptr()[base + currentByteIdx];
int currentBit = 0;
const unsigned char *currentBytePtr = byteList.ptr() + base;
const unsigned char *currentBytePtrEnd = currentBytePtr + bits.total() / 8;
for(int row = 0; row < bits.rows; row++) {
for(int col = 0; col < bits.cols; col++) {
if(currentByte >= base2List[currentBit]) {
bits.at<unsigned char>(row, col) = 1;
currentByte -= base2List[currentBit];
}
currentBit++;
if(currentBit == 8) {
currentByteIdx++;
currentByte = byteList.ptr()[base + currentByteIdx];
// if not enough bits for one more byte, we are in the end
// update bit position accordingly
if(8 * (currentByteIdx + 1) > (int)bits.total())
currentBit = 8 * (currentByteIdx + 1) - (int)bits.total();
else
currentBit = 0; // ok, bits enough for next byte
}
for(;currentBytePtr < currentBytePtrEnd; ++currentBytePtr) {
unsigned char currentByte = *currentBytePtr;
for(int mask = 1 << 7; mask != 0; mask >>= 1) {
if (currentByte & mask) *bitsPtr = 1;
++bitsPtr;
}
}
// if not enough bits for one more byte, we are in the end
// update bit position accordingly
if (bits.total() % 8 != 0) {
unsigned char currentByte = *currentBytePtrEnd;
int mask = 1 << ((bits.total() % 8) - 1);
for(; mask != 0; mask >>= 1) {
if (currentByte & mask) *bitsPtr = 1;
++bitsPtr;
}
}
return bits;