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random: fix crash on multiple early calls to add_bootloader_randomness() #4829

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merged 1 commit into from
Jan 22, 2022
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random: fix crash on multiple early calls to add_bootloader_randomness() #4829

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56 changes: 36 additions & 20 deletions drivers/char/random.c
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Original file line number Diff line number Diff line change
Expand Up @@ -461,6 +461,7 @@ static struct crng_state primary_crng = {
* its value (from 0->1->2).
*/
static int crng_init = 0;
static bool crng_need_final_init = false;
#define crng_ready() (likely(crng_init > 1))
static int crng_init_cnt = 0;
static unsigned long crng_global_init_time = 0;
Expand Down Expand Up @@ -838,6 +839,36 @@ static void __init crng_initialize_primary(struct crng_state *crng)
crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
}

static void crng_finalize_init(struct crng_state *crng)
{
if (crng != &primary_crng || crng_init >= 2)
return;
if (!system_wq) {
/* We can't call numa_crng_init until we have workqueues,
* so mark this for processing later. */
crng_need_final_init = true;
return;
}

invalidate_batched_entropy();
numa_crng_init();
crng_init = 2;
process_random_ready_list();
wake_up_interruptible(&crng_init_wait);
kill_fasync(&fasync, SIGIO, POLL_IN);
pr_notice("crng init done\n");
if (unseeded_warning.missed) {
pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
unseeded_warning.missed);
unseeded_warning.missed = 0;
}
if (urandom_warning.missed) {
pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
urandom_warning.missed);
urandom_warning.missed = 0;
}
}

#ifdef CONFIG_NUMA
static void do_numa_crng_init(struct work_struct *work)
{
Expand Down Expand Up @@ -974,25 +1005,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
memzero_explicit(&buf, sizeof(buf));
crng->init_time = jiffies;
spin_unlock_irqrestore(&crng->lock, flags);
if (crng == &primary_crng && crng_init < 2) {
invalidate_batched_entropy();
numa_crng_init();
crng_init = 2;
process_random_ready_list();
wake_up_interruptible(&crng_init_wait);
kill_fasync(&fasync, SIGIO, POLL_IN);
pr_notice("crng init done\n");
if (unseeded_warning.missed) {
pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
unseeded_warning.missed);
unseeded_warning.missed = 0;
}
if (urandom_warning.missed) {
pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
urandom_warning.missed);
urandom_warning.missed = 0;
}
}
crng_finalize_init(crng);
}

static void _extract_crng(struct crng_state *crng,
Expand Down Expand Up @@ -1799,6 +1812,8 @@ static void __init init_std_data(struct entropy_store *r)
int __init rand_initialize(void)
{
init_std_data(&input_pool);
if (crng_need_final_init)
crng_finalize_init(&primary_crng);
crng_initialize_primary(&primary_crng);
crng_global_init_time = jiffies;
if (ratelimit_disable) {
Expand Down Expand Up @@ -2307,7 +2322,8 @@ void add_hwgenerator_randomness(const char *buffer, size_t count,
* We'll be woken up again once below random_write_wakeup_thresh,
* or when the calling thread is about to terminate.
*/
wait_event_interruptible(random_write_wait, kthread_should_stop() ||
wait_event_interruptible(random_write_wait,
!system_wq || kthread_should_stop() ||
ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits);
mix_pool_bytes(poolp, buffer, count);
credit_entropy_bits(poolp, entropy);
Expand Down