[patch 41/88] mm: pass correct mm when growing stack

Greg KH
2009-04-30T17:25:47Z

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2.6.28-stable review patch. If anyone has any objections, please let us know.

------------------

From: Hugh Dickins <hugh@veritas.com>

upstream commit: 05fa199d45c54a9bda7aa3ae6537253d6f097aa9

Tetsuo Handa reports seeing the WARN_ON(current->mm == NULL) in
security_vm_enough_memory(), when do_execve() is touching the
target mm's stack, to set up its args and environment.

Yes, a UMH_NO_WAIT or UMH_WAIT_PROC call_usermodehelper() spawns
an mm-less kernel thread to do the exec. And in any case, that
vm_enough_memory check when growing stack ought to be done on the
target mm, not on the execer's mm (though apart from the warning,
it only makes a slight tweak to OVERCOMMIT_NEVER behaviour).

Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
mm/mmap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1580,7 +1580,7 @@ static int acct_stack_growth(struct vm_a
* Overcommit.. This must be the final test, as it will
* update security statistics.
*/
- if (security_vm_enough_memory(grow))
+ if (security_vm_enough_memory_mm(mm, grow))
return -ENOMEM;

/* Ok, everything looks good - let it rip */