In Android before 2018-04-05 or earlier security patch level on Qualcomm Snapdragon Automobile, Snapdragon Mobile, Snapdragon Wear, and Small Cell SoC FSM9055, IPQ4019, MDM9206, MDM9607, MDM9625, MDM9635M, MDM9640, MDM9645, MDM9650, MDM9655, MSM8909W, SD 210/SD 212/SD 205, SD 400, SD 410/12, SD 425, SD 430, SD 450, SD 600, SD 615/16/SD 415, SD 617, SD 625, SD 650/52, SD 800, SD 808, SD 810, SD 820, SD 820A, SD 835, SD 845, SD 850, and SDX20, when an RSA encryption operation is called, the ce_util_to_unsigned_bin is invoked to convert the input buffer to unsigned binary. The ce_util_to_unsigned_bin function, instead of operating on the size of the unsigned character buffer that is passed, operates on the address - i.e. operates on "c" instead of "*c". Decrementing the address to check if it is less than zero means that the operation will always pass, since a pointer will never be less than zero, and may result in a buffer overflow.