mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-21 08:19:28 +00:00
![Andy Lutomirski](/assets/img/avatar_default.png)
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 <luto@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Rik van Riel <riel@surriel.com> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Jann Horn <jannh@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/dd956eba16646fd0b15c3c0741269dfd84452dac.1535557289.git.luto@kernel.org
38 lines
845 B
C
38 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);
|