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Commit 6a029a90 authored by Al Viro's avatar Al Viro Committed by Linus Torvalds
Browse files

[PATCH] mmaper_kern.c fixes [buffer overruns] 



 - copy_from_user() can fail; ->write() must check its return value.

 - severe buffer overruns both in ->read() and ->write() - lseek to the
   end (i.e.  to mmapper_size) and

	if (count + *ppos > mmapper_size)
		count = count + *ppos - mmapper_size;

   will do absolutely nothing.  Then it will call

	copy_to_user(buf,&v_buf[*ppos],count);

   with obvious results (similar for ->write()).

   Fixed by turning read to simple_read_from_buffer() and by doing
   normal limiting of count in ->write().

 - gratitious lock_kernel() in ->mmap() - it's useless there.

 - lots of gratuitous includes.

Signed-off-by: default avatarAl Viro <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 36676bcb

arch/um/drivers/mmapper_kern.c

+9 −32
Original line number Diff line number Diff line
@@ -9,19 +9,11 @@ 
 *

 */



#include <linux/types.h>

#include <linux/kdev_t.h>

#include <linux/time.h>

#include <linux/devfs_fs_kernel.h>

#include <linux/init.h> 

#include <linux/module.h>

#include <linux/mm.h> 

#include <linux/slab.h>

#include <linux/init.h> 

#include <linux/smp_lock.h>

#include <linux/miscdevice.h>

#include <asm/uaccess.h>

#include <asm/irq.h>

#include <asm/pgtable.h>

#include "mem_user.h"

#include "user_util.h"
@@ -31,35 +23,22 @@ static unsigned long p_buf = 0; 
static char *v_buf = NULL;



static ssize_t

mmapper_read(struct file *file, char *buf, size_t count, loff_t *ppos)

mmapper_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)

{

	if(*ppos > mmapper_size)

		return -EINVAL;



	if(count + *ppos > mmapper_size)

		count = count + *ppos - mmapper_size;



	if(count < 0)

		return -EINVAL;

 

	copy_to_user(buf,&v_buf[*ppos],count);

	

	return count;

	return simple_read_from_buffer(buf, count, ppos, v_buf, mmapper_size);

}



static ssize_t

mmapper_write(struct file *file, const char *buf, size_t count, loff_t *ppos)

mmapper_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)

{

	if (*ppos > mmapper_size)

		return -EINVAL;



	if(count + *ppos > mmapper_size)

		count = count + *ppos - mmapper_size;



	if(count < 0)

		return -EINVAL;

	if (count > mmapper_size - *ppos)

		count = mmapper_size - *ppos;



	copy_from_user(&v_buf[*ppos],buf,count);

	if (copy_from_user(&v_buf[*ppos], buf, count))

		return -EFAULT;

	

	return count;

}
@@ -77,7 +56,6 @@ mmapper_mmap(struct file *file, struct vm_area_struct * vma) 
	int ret = -EINVAL;

	int size;



	lock_kernel();

	if (vma->vm_pgoff != 0)

		goto out;
@@ -92,7 +70,6 @@ mmapper_mmap(struct file *file, struct vm_area_struct * vma) 
		goto out;

	ret = 0;

out:

	unlock_kernel();

	return ret;

}