[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>
diff --git a/arch/um/drivers/mmapper_kern.c b/arch/um/drivers/mmapper_kern.c
index a37a5ac..022f67b 100644
--- a/arch/um/drivers/mmapper_kern.c
+++ b/arch/um/drivers/mmapper_kern.c
@@ -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 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 @@
int ret = -EINVAL;
int size;
- lock_kernel();
if (vma->vm_pgoff != 0)
goto out;
@@ -92,7 +70,6 @@
goto out;
ret = 0;
out:
- unlock_kernel();
return ret;
}
