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authorTheodore Ts'o <tytso@mit.edu>2019-05-22 12:02:16 -0400
committerTheodore Ts'o <tytso@mit.edu>2019-05-26 00:11:49 -0400
commit58be0106c5306b939b07b4b8bf00669a20593f4b (patch)
treed606e36cf1ad7fc39da0a980db7d718f3730b875 /drivers
parentb7d5dc21072cda7124d13eae2aefb7343ef94197 (diff)
downloadlinux-58be0106c5306b939b07b4b8bf00669a20593f4b.tar.gz
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/char/random.c16
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;
}