mirror of
https://github.com/torvalds/linux.git
synced 2024-11-05 03:21:32 +00:00
efdc1e2083
Instead of doing byte-at-a-time user accesses to figure out where the fault occurred, read the saved fault_address from the current thread structure. For the sake of defensive programming, if the fault_address does not fall into the user buffer range, simply assume the whole area faulted. This will cause the fixup for copy_from_user() to clear the entire kernel side buffer. Signed-off-by: David S. Miller <davem@davemloft.net>
67 lines
1.6 KiB
C
67 lines
1.6 KiB
C
/* user_fixup.c: Fix up user copy faults.
|
|
*
|
|
* Copyright (C) 2004 David S. Miller <davem@redhat.com>
|
|
*/
|
|
|
|
#include <linux/compiler.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/string.h>
|
|
#include <linux/errno.h>
|
|
#include <asm/uaccess.h>
|
|
|
|
/* Calculating the exact fault address when using
|
|
* block loads and stores can be very complicated.
|
|
*
|
|
* Instead of trying to be clever and handling all
|
|
* of the cases, just fix things up simply here.
|
|
*/
|
|
|
|
static unsigned long compute_size(unsigned long start, unsigned long size, unsigned long *offset)
|
|
{
|
|
unsigned long fault_addr = current_thread_info()->fault_address;
|
|
unsigned long end = start + size;
|
|
|
|
if (fault_addr < start || fault_addr >= end) {
|
|
*offset = 0;
|
|
} else {
|
|
*offset = start - fault_addr;
|
|
size = end - fault_addr;
|
|
}
|
|
return size;
|
|
}
|
|
|
|
unsigned long copy_from_user_fixup(void *to, const void __user *from, unsigned long size)
|
|
{
|
|
unsigned long offset;
|
|
|
|
size = compute_size((unsigned long) from, size, &offset);
|
|
if (likely(size))
|
|
memset(to + offset, 0, size);
|
|
|
|
return size;
|
|
}
|
|
|
|
unsigned long copy_to_user_fixup(void __user *to, const void *from, unsigned long size)
|
|
{
|
|
unsigned long offset;
|
|
|
|
return compute_size((unsigned long) to, size, &offset);
|
|
}
|
|
|
|
unsigned long copy_in_user_fixup(void __user *to, void __user *from, unsigned long size)
|
|
{
|
|
unsigned long fault_addr = current_thread_info()->fault_address;
|
|
unsigned long start = (unsigned long) to;
|
|
unsigned long end = start + size;
|
|
|
|
if (fault_addr >= start && fault_addr < end)
|
|
return end - fault_addr;
|
|
|
|
start = (unsigned long) from;
|
|
end = start + size;
|
|
if (fault_addr >= start && fault_addr < end)
|
|
return end - fault_addr;
|
|
|
|
return size;
|
|
}
|