Commit 736f24d5 authored Jun 07, 2012 by Cyrill Gorcunov Committed by Linus Torvalds Jun 07, 2012

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



In commit b7643757 ("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 <gorcunov@openvz.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 300f786b

kernel/sys.c

+0 −14

Original line number	Diff line number	Diff line
		@@ -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)

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