Re: [syzbot] [crypto?] INFO: task hung in hwrng_fillfn

[syzbot <syzbot+c52ab18308964d248092@syzkaller.appspotmail.com>]

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Subject: [crypto?] INFO: task hung in hwrng_fillfn
Author: eadavis@qq.com

please test task hung in hwrng_fillfn

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 98b1cc82c4af

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index 420f155d251f..ebfa5eab84df 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -501,7 +501,10 @@ static int hwrng_fillfn(void *unused)
 		rng = get_current_rng();
 		if (IS_ERR(rng) || !rng)
 			break;
-		mutex_lock(&reading_mutex);
+		if (mutex_lock_interruptible(&reading_mutex)) {
+			put_rng(rng);
+			return = -ERESTARTSYS;
+		}
 		rc = rng_get_data(rng, rng_fillbuf,
 				  rng_buffer_size(), 1);
 		if (current_quality != rng->quality)