maxpad |= (255 - maxpad) >> (sizeof(maxpad) * 8 - 8);
maxpad &= 255;
- ret &= constant_time_ge(maxpad, pad);
+ mask = constant_time_ge(maxpad, pad);
+ ret &= mask;
+ /*
+ * If pad is invalid then we will fail the above test but we must
+ * continue anyway because we are in constant time code. However,
+ * we'll use the maxpad value instead of the supplied pad to make
+ * sure we perform well defined pointer arithmetic.
+ */
+ pad = constant_time_select(mask, pad, maxpad);
inp_len = len - (SHA_DIGEST_LENGTH + pad + 1);
mask = (0 - ((inp_len - len) >> (sizeof(inp_len) * 8 - 1)));