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[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: Al Viro <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Al Viro 2005-08-27 06:48:15 +01:00 committed by Linus Torvalds
parent 36676bcbf9
commit 6a029a90f5
1 changed files with 9 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
arch/um/drivers/mmapper_kern.c
View File

@ -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)
if (*ppos > mmapper_size)
return -EINVAL;
if(count + *ppos > mmapper_size)
count = count + *ppos - mmapper_size;
if (count > mmapper_size - *ppos)
count = mmapper_size - *ppos;
if(count < 0)
return -EINVAL;
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;
}