mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git
synced 2026-11-09 19:10:45 +01:00
Andy Lutomirski
4012e77a90
A NMI can hit in the middle of context switching or in the middle of switch_mm_irqs_off(). In either case, CR3 might not match current->mm, which could cause copy_from_user_nmi() and friends to read the wrong memory. Fix it by adding a new nmi_uaccess_okay() helper and checking it in copy_from_user_nmi() and in __copy_from_user_nmi()'s callers. Signed-off-by: Andy Lutomirski <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Reviewed-by: Rik van Riel <[email protected]> Cc: Nadav Amit <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Jann Horn <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: [email protected] Link: https://lkml.kernel.org/r/dd956eba16646fd0b15c3c0741269dfd84452dac.1535557289.git.luto@kernel.org
39 lines
845 B
C
39 lines
845 B
C
/*
|
|
* User address space access functions.
|
|
*
|
|
* For licencing details see kernel-base/COPYING
|
|
*/
|
|
|
|
#include <linux/uaccess.h>
|
|
#include <linux/export.h>
|
|
|
|
#include <asm/tlbflush.h>
|
|
|
|
/*
|
|
* We rely on the nested NMI work to allow atomic faults from the NMI path; the
|
|
* nested NMI paths are careful to preserve CR2.
|
|
*/
|
|
unsigned long
|
|
copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
|
|
{
|
|
unsigned long ret;
|
|
|
|
if (__range_not_ok(from, n, TASK_SIZE))
|
|
return n;
|
|
|
|
if (!nmi_uaccess_okay())
|
|
return n;
|
|
|
|
/*
|
|
* Even though this function is typically called from NMI/IRQ context
|
|
* disable pagefaults so that its behaviour is consistent even when
|
|
* called form other contexts.
|
|
*/
|
|
pagefault_disable();
|
|
ret = __copy_from_user_inatomic(to, from, n);
|
|
pagefault_enable();
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(copy_from_user_nmi);
|