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random: fix soft lockup when trying to read from an uninitialized blocking pool 

Fixes: eb9d1bf079bb: "random: only read from /dev/random after its pool has received 128 bits"
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o 2019-05-22 12:02:16 -04:00
parent b7d5dc2107
commit 58be0106c5
1 changed files with 13 additions and 3 deletions
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16
drivers/char/random.c
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@ -772,8 +772,11 @@ retry:
if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
goto retry;
if (has_initialized)
if (has_initialized) {
r->initialized = 1;
wake_up_interruptible(&random_read_wait);
kill_fasync(&fasync, SIGIO, POLL_IN);
}
trace_credit_entropy_bits(r->name, nbits,
entropy_count >> ENTROPY_SHIFT, _RET_IP_);
@ -789,6 +792,13 @@ retry:
entropy_bits = r->entropy_count >> ENTROPY_SHIFT;
}
/* initialize the blocking pool if necessary */
if (entropy_bits >= random_read_wakeup_bits &&
!other->initialized) {
schedule_work(&other->push_work);
return;
}
/* should we wake readers? */
if (entropy_bits >= random_read_wakeup_bits &&
wq_has_sleeper(&random_read_wait)) {
@ -1936,8 +1946,8 @@ _random_read(int nonblock, char __user *buf, size_t nbytes)
return -EAGAIN;
wait_event_interruptible(random_read_wait,
ENTROPY_BITS(&input_pool) >=
random_read_wakeup_bits);
blocking_pool.initialized &&
(ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits));
if (signal_pending(current))
return -ERESTARTSYS;
}