extractbits robustness

This commit is contained in:
Ameer J 2023-07-30 13:05:45 -04:00
parent 0078e5a338
commit d17a51bc59

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@ -349,14 +349,17 @@ uint ExtractBits(uvec4 payload, int offset, int bits) {
if (bits <= 0) { if (bits <= 0) {
return 0; return 0;
} }
int last_offset = offset + bits - 1; if (bits > 32) {
int shifted_offset = offset >> 5; return 0;
}
const int last_offset = offset + bits - 1;
const int shifted_offset = offset >> 5;
if ((last_offset >> 5) == shifted_offset) { if ((last_offset >> 5) == shifted_offset) {
return bitfieldExtract(payload[shifted_offset], offset & 31, bits); return bitfieldExtract(payload[shifted_offset], offset & 31, bits);
} }
int first_bits = 32 - (offset & 31); const int first_bits = 32 - (offset & 31);
int result_first = int(bitfieldExtract(payload[shifted_offset], offset & 31, first_bits)); const int result_first = int(bitfieldExtract(payload[shifted_offset], offset & 31, first_bits));
int result_second = int(bitfieldExtract(payload[shifted_offset + 1], 0, bits - first_bits)); const int result_second = int(bitfieldExtract(payload[shifted_offset + 1], 0, bits - first_bits));
return result_first | (result_second << first_bits); return result_first | (result_second << first_bits);
} }