Am Donnerstag, 17. August 2017, 20:25:17 CEST schrieb PrasannaKumar Muralidharan: Hi PrasannaKumar, > + > +static int jz4780_rng_generate(struct crypto_rng *tfm, > + const u8 *src, unsigned int slen, > + u8 *dst, unsigned int dlen) > +{ > + struct jz4780_rng_ctx *ctx = crypto_rng_ctx(tfm); > + struct jz4780_rng *rng = ctx->rng; > + u32 data; > + > + /* > + * JZ4780 Programmers manual says the RNG should not run continuously > + * for more than 1s. So enable RNG, read data and disable it. > + * NOTE: No issue was observed with MIPS creator CI20 board even when > + * RNG ran continuously for longer periods. This is just a precaution. > + * > + * A delay is required so that the current RNG data is not bit shifted > + * version of previous RNG data which could happen if random data is > + * read continuously from this device. > + */ > + jz4780_rng_writel(rng, 1, REG_RNG_CTRL); > + do { > + data = jz4780_rng_readl(rng, REG_RNG_DATA); > + memcpy((void *)dst, (void *)&data, 4); How do you know that dst is a multiple of 4 bytes? When dlen is only 3, you overflow the buffer. > + dlen -= 4; > + dst += 4; > + udelay(20); > + } while (dlen >= 4); > + > + if (dlen > 0) { > + data = jz4780_rng_readl(rng, REG_RNG_DATA); > + memcpy((void *)dst, (void *)&data, dlen); > + } > + jz4780_rng_writel(rng, 0, REG_RNG_CTRL); > + > + return 0; > +} Ciao Stephan