This is a note to let you know that I've just added the patch titled
random: wake up /dev/random writers after zap
to the 5.16-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
random-wake-up-dev-random-writers-after-zap.patch
and it can be found in the queue-5.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 8117aa36f6b7e3e28f6b285915cd2536cfc95a65
Author: Jason A. Donenfeld <Jason@xxxxxxxxx>
Date: Fri Jan 28 23:44:03 2022 +0100
random: wake up /dev/random writers after zap
[ Upstream commit 042e293e16e3aa9794ce60c29f5b7b0c8170f933 ]
When account() is called, and the amount of entropy dips below
random_write_wakeup_bits, we wake up the random writers, so that they
can write some more in. However, the RNDZAPENTCNT/RNDCLEARPOOL ioctl
sets the entropy count to zero -- a potential reduction just like
account() -- but does not unblock writers. This commit adds the missing
logic to that ioctl to unblock waiting writers.
Reviewed-by: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/char/random.c b/drivers/char/random.c
index a27ae3999ff32..ebe86de9d0acc 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1963,7 +1963,10 @@ static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
*/
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- input_pool.entropy_count = 0;
+ if (xchg(&input_pool.entropy_count, 0) && random_write_wakeup_bits) {
+ wake_up_interruptible(&random_write_wait);
+ kill_fasync(&fasync, SIGIO, POLL_OUT);
+ }
return 0;
case RNDRESEEDCRNG:
if (!capable(CAP_SYS_ADMIN))
