[lkml]   [2021]   [Dec]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH v8 2/7] random: do not re-init if crng_reseed completes before primary init
From: "Jason A. Donenfeld" <>

If the bootloader supplies sufficient material and crng_reseed() is called
very early on, but not too early that wqs aren't available yet, then we
might transition to crng_init==2 before rand_initialize()'s call to
crng_initialize_primary() made. Then, when crng_initialize_primary() is
called, if we're trusting the CPU's RDRAND instructions, we'll
needlessly reinitialize the RNG and emit a message about it. This is
mostly harmless, as numa_crng_init() will allocate and then free what it
just allocated, and excessive calls to invalidate_batched_entropy()
aren't so harmful. But it is funky and the extra message is confusing,
so avoid the re-initialization all together by checking for crng_init <
2 in crng_initialize_primary(), just as we already do in crng_reseed().

Reviewed-by: Dominik Brodowski <>
Signed-off-by: Jason A. Donenfeld <>
drivers/char/random.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 144e8841bff4..916cf791ed0e 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -827,7 +827,7 @@ static void __init crng_initialize_primary(struct crng_state *crng)
_extract_entropy(&input_pool, &crng->state[4], sizeof(__u32) * 12, 0);
- if (crng_init_try_arch_early(crng) && trust_cpu) {
+ if (crng_init_try_arch_early(crng) && trust_cpu && crng_init < 2) {
crng_init = 2;
 \ /
  Last update: 2021-12-29 22:14    [W:0.117 / U:0.840 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site