diff options
| author | Theodore Ts'o <tytso@mit.edu> | 2019-05-22 12:02:16 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2019-05-26 00:11:49 -0400 |
| commit | 58be0106c5306b939b07b4b8bf00669a20593f4b (patch) | |
| tree | d606e36cf1ad7fc39da0a980db7d718f3730b875 | |
| parent | b7d5dc21072cda7124d13eae2aefb7343ef94197 (diff) | |
| download | lwn-58be0106c5306b939b07b4b8bf00669a20593f4b.tar.gz lwn-58be0106c5306b939b07b4b8bf00669a20593f4b.zip | |
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>
| -rw-r--r-- | drivers/char/random.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index a42b3d764da8..5d5ea4ce1442 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -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; } |