From e64f57e8cd5abe167cdf453869d6274608480519 Mon Sep 17 00:00:00 2001 From: Tomas Marek Date: Wed, 12 Oct 2022 18:09:24 +0200 Subject: hwrng: stm32 - fix read of the last word The stm32_rng_read() function samples TRNG by 4 bytes until at least 5 bytes are free in the input buffer. The last four bytes are never read. For example, 60 bytes are returned in case the input buffer size is 64 bytes. Read until at least 4 bytes are free in the input buffer. Fill the buffer entirely in case the buffer size is divisible by 4. Cc: Oleg Karfich Signed-off-by: Tomas Marek Signed-off-by: Herbert Xu --- drivers/char/hw_random/stm32-rng.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/char') diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c index 8eaacefd498b..366edda4848b 100644 --- a/drivers/char/hw_random/stm32-rng.c +++ b/drivers/char/hw_random/stm32-rng.c @@ -44,7 +44,7 @@ static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) pm_runtime_get_sync((struct device *) priv->rng.priv); - while (max > sizeof(u32)) { + while (max >= sizeof(u32)) { sr = readl_relaxed(priv->base + RNG_SR); /* Manage timeout which is based on timer and take */ /* care of initial delay time when enabling rng */ -- cgit v1.2.3