c/r: prctl: drop VMA flags test on PR_SET_MM_ stack data assignment

In commit b764375 ("procfs: mark thread stack correctly in proc/<pid>/maps") the stack allocated via clone() is marked in /proc/<pid>/maps as [stack:%d] thus it might be out of the former mm->start_stack/end_stack values (and even has some custom VMA flags set). So to be able to restore mm->start_stack/end_stack drop vma flags test, but still require the underlying VMA to exist. As always note this feature is under CONFIG_CHECKPOINT_RESTORE and requires CAP_SYS_RESOURCE to be granted. Signed-off-by: Cyrill Gorcunov <[email protected]> Cc: Oleg Nesterov <[email protected]> Acked-by: Kees Cook <[email protected]> Cc: Pavel Emelyanov <[email protected]> Cc: Serge Hallyn <[email protected]> Cc: KAMEZAWA Hiroyuki <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
chewitt · Jun 7, 2012 · 736f24d · 736f24d
1 parent 300f786
commit 736f24d
Showing 1 changed file with 0 additions and 14 deletions.
diff --git a/kernel/sys.c b/kernel/sys.c
@@ -1786,14 +1786,6 @@ SYSCALL_DEFINE1(umask, int, mask)
 }
 
 #ifdef CONFIG_CHECKPOINT_RESTORE
-static bool vma_flags_mismatch(struct vm_area_struct *vma,
-			       unsigned long required,
-			       unsigned long banned)
-{
-	return (vma->vm_flags & required) != required ||
-		(vma->vm_flags & banned);
-}
-
 static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
 {
 	struct vm_area_struct *vma;
@@ -1931,12 +1923,6 @@ static int prctl_set_mm(int opt, unsigned long addr,
 			error = -EFAULT;
 			goto out;
 		}
-#ifdef CONFIG_STACK_GROWSUP
-		if (vma_flags_mismatch(vma, VM_READ | VM_WRITE | VM_GROWSUP, 0))
-#else
-		if (vma_flags_mismatch(vma, VM_READ | VM_WRITE | VM_GROWSDOWN, 0))
-#endif
-			goto out;
 		if (opt == PR_SET_MM_START_STACK)
 			mm->start_stack = addr;
 		else if (opt == PR_SET_MM_ARG_START)