| From | Andy Lutomirski <> | Subject | [PATCH v5 13/32] x86/mm/64: In vmalloc_fault(), use CR3 instead of current->active_mm | Date | Mon, 11 Jul 2016 13:53:46 -0700 |
| |
If we get a vmalloc fault while current->active_mm->pgd doesn't match CR3, we'll crash without this change. I've seen this failure mode on heavily instrumented kernels with virtually mapped stacks.
Signed-off-by: Andy Lutomirski <luto@kernel.org> --- arch/x86/mm/fault.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 7d1fa7cd2374..ca44e2e7fd00 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -439,7 +439,7 @@ static noinline int vmalloc_fault(unsigned long address) * happen within a race in page table update. In the later * case just flush: */ - pgd = pgd_offset(current->active_mm, address); + pgd = (pgd_t *)__va(read_cr3()) + pgd_index(address); pgd_ref = pgd_offset_k(address); if (pgd_none(*pgd_ref)) return -1; -- 2.7.4
|