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Message-ID: <000000000000051b7b060b0650d4@google.com>
Date: Sat, 25 Nov 2023 20:06:40 -0800
From: syzbot <syzbot+c52ab18308964d248092@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org
Subject: Re: [syzbot] [crypto?] INFO: task hung in hwrng_fillfn
For archival purposes, forwarding an incoming command email to
linux-kernel@...r.kernel.org.
***
Subject: [crypto?] INFO: task hung in hwrng_fillfn
Author: eadavis@...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..883412bbf9f2 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -225,17 +225,18 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf,
goto out;
}
- if (mutex_lock_interruptible(&reading_mutex)) {
- err = -ERESTARTSYS;
- goto out_put;
- }
if (!data_avail) {
+ if (mutex_lock_interruptible(&reading_mutex)) {
+ err = -ERESTARTSYS;
+ goto out_put;
+ }
bytes_read = rng_get_data(rng, rng_buffer,
rng_buffer_size(),
!(filp->f_flags & O_NONBLOCK));
+ mutex_unlock(&reading_mutex);
if (bytes_read < 0) {
err = bytes_read;
- goto out_unlock_reading;
+ goto out_put;
}
data_avail = bytes_read;
}
@@ -243,7 +244,7 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf,
if (!data_avail) {
if (filp->f_flags & O_NONBLOCK) {
err = -EAGAIN;
- goto out_unlock_reading;
+ goto out_put;
}
} else {
len = data_avail;
@@ -255,14 +256,13 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf,
if (copy_to_user(buf + ret, rng_buffer + data_avail,
len)) {
err = -EFAULT;
- goto out_unlock_reading;
+ goto out_put;
}
size -= len;
ret += len;
}
- mutex_unlock(&reading_mutex);
put_rng(rng);
if (need_resched())
@@ -276,8 +276,6 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf,
out:
return ret ? : err;
-out_unlock_reading:
- mutex_unlock(&reading_mutex);
out_put:
put_rng(rng);
goto out;
@@ -501,7 +499,10 @@ 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)
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