Unverified Commit e06ea6c8 authored by openeuler-ci-bot's avatar openeuler-ci-bot Committed by Gitee
Browse files

!7644 hwrng: core - Fix page fault dead lock on mmap-ed hwrng 

Merge Pull Request from: @ci-robot 
 
PR sync from: Guo Mengqi <guomengqi3@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/5R4OGZAELMY4DT74ZM6YDXBLVIROSBBW/ 
 
https://gitee.com/src-openeuler/kernel/issues/I99JR3 
 
Link:https://gitee.com/openeuler/kernel/pulls/7644

 

Reviewed-by: default avatarJialin Zhang <zhangjialin11@huawei.com>
Signed-off-by: default avatarJialin Zhang <zhangjialin11@huawei.com>
parents 344a02cd f2105e30

drivers/char/hw_random/core.c

+21 −13
Original line number Diff line number Diff line
@@ -24,10 +24,13 @@ 
#include <linux/random.h>

#include <linux/sched.h>

#include <linux/slab.h>

#include <linux/string.h>

#include <linux/uaccess.h>



#define RNG_MODULE_NAME		"hw_random"



#define RNG_BUFFER_SIZE (SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES)



static struct hwrng *current_rng;

/* the current rng has been explicitly chosen by user via sysfs */

static int cur_rng_set_by_user;
@@ -59,7 +62,7 @@ static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size, 


static size_t rng_buffer_size(void)

{

	return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES;

	return RNG_BUFFER_SIZE;

}



static void add_early_randomness(struct hwrng *rng)
@@ -206,6 +209,7 @@ static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size, 
static ssize_t rng_dev_read(struct file *filp, char __user *buf,

			    size_t size, loff_t *offp)

{

	u8 buffer[RNG_BUFFER_SIZE];

	ssize_t ret = 0;

	int err = 0;

	int bytes_read, len;
@@ -233,34 +237,37 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf, 
			if (bytes_read < 0) {

				err = bytes_read;

				goto out_unlock_reading;

			} else if (bytes_read == 0 &&

				   (filp->f_flags & O_NONBLOCK)) {

				err = -EAGAIN;

				goto out_unlock_reading;

			}



			data_avail = bytes_read;

		}



		if (!data_avail) {

			if (filp->f_flags & O_NONBLOCK) {

				err = -EAGAIN;

				goto out_unlock_reading;

			}

		} else {

		len = data_avail;

		if (len) {

			if (len > size)

				len = size;



			data_avail -= len;



			if (copy_to_user(buf + ret, rng_buffer + data_avail,

								len)) {

			memcpy(buffer, rng_buffer + data_avail, len);

		}

		mutex_unlock(&reading_mutex);

		put_rng(rng);



		if (len) {

			if (copy_to_user(buf + ret, buffer, len)) {

				err = -EFAULT;

				goto out_unlock_reading;

				goto out;

			}



			size -= len;

			ret += len;

		}



		mutex_unlock(&reading_mutex);

		put_rng(rng);



		if (need_resched())

			schedule_timeout_interruptible(1);
@@ -271,6 +278,7 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf, 
		}

	}

out:

	memzero_explicit(buffer, sizeof(buffer));

	return ret ? : err;



out_unlock_reading: