From: Jason A. Donenfeld <Jason@zx2c4.com>
Date: Fri, 23 Sep 2022 00:42:51 +0000 (+0200)
Subject: random: clamp credited irq bits to maximum mixed
X-Git-Tag: v6.1-rc1~91^2~11
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=e78a802a7b4febf53f2a92842f494b01062d85a8;p=linux-block.git

random: clamp credited irq bits to maximum mixed

Since the most that's mixed into the pool is sizeof(long)*2, don't
credit more than that many bytes of entropy.

Fixes: e3e33fc2ea7f ("random: do not use input pool from hard IRQs")
Cc: stable@vger.kernel.org
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 520a385c7dab..2f370aa248b2 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1004,7 +1004,7 @@ static void mix_interrupt_randomness(struct work_struct *work)
 	local_irq_enable();
 
 	mix_pool_bytes(pool, sizeof(pool));
-	credit_init_bits(max(1u, (count & U16_MAX) / 64));
+	credit_init_bits(clamp_t(unsigned int, (count & U16_MAX) / 64, 1, sizeof(pool) * 8));
 
 	memzero_explicit(pool, sizeof(pool));
 }